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This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- ** Missing document type: Expected "INTERNET-DRAFT" in the upper left hand corner of the first page == There are 51 instances of lines with non-ascii characters in the document. == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an Introduction section. (A line matching the expected section header was found, but with an unexpected indentation: ' 1. Introduction and Overview' ) ** The document seems to lack a Security Considerations section. (A line matching the expected section header was found, but with an unexpected indentation: ' 8. Security Considerations' ) ** The document seems to lack an IANA Considerations section. (See Section 2.2 of https://www.ietf.org/id-info/checklist for how to handle the case when there are no actions for IANA.) ** There are 1121 instances of too long lines in the document, the longest one being 15 characters in excess of 72. ** The abstract seems to contain references ([2], [3], [4], [5], [6], [7]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'SHALL not' in this paragraph: It SHALL be possible to address private numbers (extensions) within an administrative as defined in ITU-T Rec. E.164 Annex B.3.2 by an ISDN Number to be reached either with Direct-Dialing-In (DDI) (Overdialing) or via MSN. This implies that the private numbering plan maps to the E.164 numbers as partial numbers. Sub-addressing (network address extensions) SHALL not be used. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'SHALL not' in this paragraph: Administrative domains may provide network specific numbers for internal use only. This numbers SHALL not be reachable from the outside, since they are NOT E.164 numbers. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (October 2003) is 7498 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Missing reference section? '1' on line 15 looks like a reference -- Missing reference section? '2' on line 46 looks like a reference -- Missing reference section? '3' on line 104 looks like a reference -- Missing reference section? '4' on line 181 looks like a reference -- Missing reference section? '5' on line 197 looks like a reference -- Missing reference section? '6' on line 212 looks like a reference -- Missing reference section? '7' on line 1991 looks like a reference Summary: 7 errors (**), 0 flaws (~~), 5 warnings (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IETF ENUM WG 3 Internet Draft R Stastny 4 Document: OeFEG 5 draft-stastny-enum-numbering-voip-00.txt 6 Expires: April 2004 October 2003 7 Informational 9 Numbering for VoIP and other IP Communications 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC2026 [1]. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 Abstract 33 This document gives advice in setting up E.164 compatible numbering 34 and dialing plans in administrative domains set up for IP 35 Communications in general and VoIP applications in detail. After 36 explaining numbering and dialing plans in principle, it discusses 37 which types of E.164 numbers should be used for IP based terminals, 38 to achieve proper routing of calls and other communications on the 39 PSTN/ISDN and also on the Internet, using ENUM technology. 41 Conventions used in this document 43 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 44 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 45 document are to be interpreted as described in RFC-2119 [2]. 47 Table of Contents 48 1. Introduction and Overview......................................2 49 2. The Problem....................................................4 50 2.1 IP Communications as Applications on the Internet..........4 51 2.2 How to reach VoIP users from the PSTN/ISDN.................4 52 2.3 The Global Public Telephony Service........................5 53 2.4 ENUM.......................................................5 54 2.5 Why using E.164 numbers natively on the Internet?..........7 55 3. Numbering and Dialing plans....................................8 56 3.1 Numbering Plans............................................8 57 3.2 Types of Numbering Plans...................................9 58 3.3 Dialing Plans.............................................12 59 4. Types of numbers in existing numbering plans..................16 60 4.1 International Public Telecommunication Numbers (E.164 Numbers) 61 ..............................................................16 62 4.2 National E.164 Numbers....................................18 63 4.3 Partial Numbers...........................................23 64 4.4 Calling line identification (CLI).........................25 65 5. E.164 Numbers for VoIP........................................26 66 5.1 E.164 Numbers for VoIP-only...............................26 67 5.2 Potential E.164 Number types for VoIP-only................27 68 6. How to set up numbering and dialing plans for VoIP domains....28 69 6.1 Basic Requirements........................................28 70 6.2 Which E.164 Numbers to use for mapping of partial numbers?30 71 6.3 Dialing Plans for administrative domains..................31 72 6.4 Numbering Plans for administrative domains................34 73 7. Routing of calls to E.164 numbers terminating on VoIP.........36 74 7.1 Routing on the PSTN.......................................37 75 7.2 ENUM Support for Routing of E.164 numbers on the Internet.39 76 7.3 Routing from Gateways and between domains with ENUM.......39 77 8. Security Considerations.......................................42 78 Author's Addresses...............................................43 80 1. Introduction and Overview 82 Currently a number of Administrative Domains for IP communications 83 are implemented allowing users to register IP phones or soft clients 84 and place VoIP calls or establish other types of IP communications 85 via broadband connections to other users registered in the same or in 86 other administrative domains by using Internet Naming and Addressing 87 schemes. 89 As a courtesy to users having only IP phones with numeric keypads or 90 terminal adaptors for steam phones, numeric aliases are used 91 exclusively or in addition. This allows users placing calls using 92 dialing strings. For "cross trunks" or "cross connections" to other 93 administrative domains and to the PSTN/ISDN different combinations of 94 access codes are implemented in an ad-hoc uncoordinated manner. 96 The advantage of this approach is that registered users may be 97 reached also from the PSTN/ISDN and other administrative domains if a 98 proper mapping of E.164 numbers to these numeric aliases as partial 99 numbers is achieved. 101 This situation is similar to the mess existing in the PSTN with 102 automatic trunk dialing in the '50s of the last century and with 103 international automatic dialing in the '60s, before the International 104 Public Telecommunication Numbering Plan (E.164 numbers) [3] was 105 introduced by ITU-T (CCITT). Traces of this messy situation can still 106 be recognized in the existing national dialing and numbering plans. 107 To prevent this from happening again on the Internet, the purpose of 108 this document is to give guidance to the definition of numbering and 109 dialing plans and the provision E.164 numbers in IP � based 110 administrative domains. 112 After stating the problem, the terminology used is defined, 113 especially the definitions of numbering and dialing plans are given 114 and their differences are explained. 116 The types of number ranges used in existing numbering plans are 117 explained and a new grouping of the type of number ranges is 118 proposed: 120 � Pure geographic numbers 121 � Non-geographic numbers for private networks 122 � Non-geographic numbers for networks and personal numbers 123 (including mobile networks and personal services using VoIP networks) 124 � Non-geographic numbers for tariff related services 126 The types of number ranges usable for VoIP and IP Communications are 127 analyzed and discussed. In principle any number range could be used 128 for VoIP, but for the direct mapping of administrative domains using 129 partial numbers the usage of national geographic numbers, national 130 non-geographic numbers for private and mobile networks and global 131 numbers for networks is recommended. 133 The document explains the routing of calls to these number ranges on 134 the PSTN/ISDN to the appropriate VoIP gateways. It is also proposed 135 to use ENUM for routing of calls on the Internet from the VoIP 136 gateways used or from other administrative domains to the E.164 137 numbers hosted by these administrative domains. 139 To map administrative domains with partial numbers to E.164 numbers 140 it is necessary to set up the administrative domains with numeric 141 userinfo (aliases). It is therefore required to set up numbering and 142 dialing plans within these administrative domains. 144 These numbering and dialing plans should allow to access the own 145 users, users in other administrative domains and users on the 146 PSTN/ISDN in a consistent manner and also allow the mapping of this 147 numbering plan to the International Public Telecommunication 148 Numbering Plan E.164 as partial numbers. 150 The basic requirements and rules to achieve this are proposed in this 151 document. 153 2. The Problem 155 2.1 IP Communications as Applications on the Internet 157 IP Communications (VoIP, IP Telephony, Internet Telephony, Voice over 158 the Net, Instant Messaging, Presence, Video, etc.) are applications 159 based on the Internet (IP) protocols, and are therefore like any 160 other applications on the Internet basically using the IP addressing 161 scheme. 163 For various reasons the direct usage of the IP addressing scheme has 164 many drawbacks, most applications on the Internet use in addition a 165 more user-friendly and comfortable naming scheme. This naming scheme 166 is based on the Domain Name System (DNS) and Universal Resource 167 Locators and Identifiers (URLs, URIs). The usage of a naming scheme 168 has also an important advantage. IP addresses may dynamically change 169 and are also related to a network endpoint (device). Since a user may 170 attach to different and multiple devices, the usage of a naming 171 scheme is adding one level of indirection and therefore allows 172 addressing the user independently of the device currently used. 174 For VoIP, the most commonly used URLs and URIs are sip:, h323: and 175 tel:. These URIs are called contact addresses, if used for a specific 176 device, or Address-of-Records, if used to address a user or a generic 177 service via a location service (see RFC3261). Address-of-records 178 allow VoIP users to reach each other on the Internet and also to 179 reach users on the PSTN/ISDN, if a proper gateway is provided. This 180 can e.g. be done with the tel: URI, which contains a phone number 181 (see RFC2806bis [4]). 183 2.2 How to reach VoIP users from the PSTN/ISDN 185 On the other hand it is in most cases not possible for users on the 186 PSTN/ISDN to reach users on the Internet, because URIs cannot be 187 entered on most telephone devices and also the signaling systems are 188 not able to deal with URIs. The PSTN/ISDN is using "phone numbers", 189 mainly the numbering scheme defined in ITU-T Rec. E.164 or compatible 190 national variants. These phone numbers are called International 191 Public Telecommunication Numbers, or E.164 numbers. 193 It is therefore necessary to provide a translation service between 194 the naming and addressing (numbering) scheme used on the PSTN/ISDN 195 and the naming scheme used on the Internet. This can be done in 196 different ways; one of these translation services is ENUM (see 197 RFC2916bis [5]). 199 2.3 The Global Public Telephony Service 201 This implies that an E.164 number is attached in addition to the 202 existing Address-of-Record of a VoIP user. If a user on the PSTN/ISDN 203 is now dialing such an E.164 number the call needs to be routed to a 204 VoIP-gateway located on the boundary between the PSTN/ISDN and the 205 Internet. 207 The VoIP-gateway is translating the E.164 Number to the Address-of- 208 Record (e.g. a sip: URI) assigned to the user. The call is then 209 routed on the Internet to the VoIP user, or more precisely to the 210 VoIP server pointed to by the host part of the Address-of-Record. 211 This implies also that the VoIP application is part of the global 212 public telephony service as defined in ITU-T Rec. E.105 [6], and 213 therefore has to fulfill a minimum of basic requirements to be 214 compliant. 216 Within this document, some of these basic requirements will be 217 discussed. 219 2.4 ENUM 221 One possibility to translate E.164 numbers to URIs is ENUM. 223 ENUM is based technically on the Domain Name System and allows a 224 mapping or translation from an E.164 number to one or more URIs. ENUM 225 is achieving this by providing a distinct domain (e164.arpa) for a 226 unique and 1:1 mapping of E.164 numbers to a specific and unique 227 domain name. Within this domain name the user may store pointers to 228 URIs. This may be any URI (e.g. an e-mail address or a pointer to a 229 web-page), but specifically also a VoIP URI. Only these mappings will 230 be discussed within this document. 232 ENUM raises two questions: 234 1. Which type of E.164 numbers may be entered in ENUM? 236 The type of numbers available will be discussed later in this 237 document. 239 The current status of discussion is that geographic numbers, numbers 240 for private networks, mobile numbers and personal numbers may be used 241 in ENUM. The usage of the other numbers, especially service numbers 242 like freephone and premium rate services are under discussion. 244 2. Are E.164 numbers entered in ENUM only or additionally to existing 245 phone services? 247 The more important question is if the ENUM entries are made IN 248 ADDITION to existing phone services if the subscriber requests it 249 (opt-in) or is it required to have an ENUM entry to get a phone 250 service (infrastructure ENUM) 252 2.4.1 ENUM as additional service with opt-in (User ENUM) 254 In this case ENUM domain names are entered in ADDITION to existing 255 phone services available on the PSTN/ISDN. Therefore any call 256 originating on the PSTN/ISDN will be routed normally on the PSTN/ISDN 257 to the existing termination as usual. Only calls originating on the 258 Internet MAY query ENUM and MAY route the call to the termination on 259 the Internet given by the ENUM entry. This is called the opt-in 260 principle. 262 The called user is opting-in in ENUM, because the entry in ENUM is 263 optional. The calling user is also opting-in, because he may query 264 ENUM or not, and even if he is querying ENUM, he still may decide to 265 terminate the call on the PSTN via a gateway. 267 In this case the VoIP application is a second line service in 268 addition to the primary line on the PSTN. This approach may be 269 feasible in conjunction with other services and applications on the 270 Internet (e.g. e-mail), but it has one serious drawback for VoIP: it 271 suffers from Metcalfe's Law. 273 Metcalfe's Law states that "the usefulness, or utility, of a network 274 equals the square of the number of users", which may translate to: "a 275 new communication application will probably be stillborn anyway, 276 because the initial value will be so small that no one will have 277 sufficient incentive for purchase". 279 Is there a way to overcome this problem? Eventually by using ENUM 280 also as infrastructure service. Here users rely on ENUM regarding 281 VoIP and get used to it, so User ENUM maybe introduced later 282 additionally for other services. 284 There is another disadvantage with User ENUM: Since the E.164 285 assignments to the phone services on the PSTN/ISDN and the 286 delegations of the corresponding e164.arpa domains have to be kept in 287 sync, it has to be validated that only the proper number assignee may 288 request the corresponding ENUM domain. This requires complicated 289 validation procedures to be established. 291 2.4.2 ENUM as infrastructure service (Infrastructure ENUM) 293 If the E.164 number is entered only in ENUM, there is no 294 synchronization with PSTN/ISDN services and therefore no validation 295 necessary, which simplifies matters. The E.164 number is then used 296 natively on the Internet. 297 In this case ENUM is implemented as a kind of IN-Service on the 298 Internet to route voice and other multimedia real-time applications 299 (IP Communications) using E.164 numbers to destinations primarily on 300 the Internet. 302 The problem to be solved here is how a call originating on the 303 PSTN/ISDN may be routed to such destinations. Routing on the 304 PSTN/ISDN is still done primarily by digit analysis of the dialed 305 destination number. IN services e.g. for Number Portability (NP) are 306 available only on a local or national scale. 308 This immediately raises the question: which E.164 numbering resources 309 could be used for such destinations? 311 A simple solution is to use specific numbering resources for this 312 purpose. This would allow to route (and also bill) any call to this 313 number from the PSTN/ISDN to the nearest ENUM-enabled gateway (Point- 314 of-Interconnect). Note: this can be done even on a global scale, if 315 the first 6 to 7 digits of an E.164 number are used (e.g. CC + NDC). 316 End Note. 318 This has a severe drawback insofar that most numbering plans 319 established by the national authorities (NRA) responsible claim to be 320 technology independent (which is not completely true in all cases 321 anyway), so specific number ranges for "VoIP-only" are currently not 322 possible in some countries and also not on a global scale. Although 323 this may change, other possibilities need to be considered. This 324 document will try to propose different solutions for this problem. 326 2.5 Why using E.164 numbers natively on the Internet? 328 It was stated above that users on the Internet may use URIs to 329 communicate with each other. Although this is true in principle, the 330 usage of phone numbers also has advantages. 332 Some existing Administrative Domains implementing VoIP and other IP 333 Communications use numbers to identify their user agents 334 (subscribers). This may be done either directly by giving the user 335 agents a numeric user(info) to be used in the sip: URI or h323: URI 336 Address-of-Record, or by providing them in addition with an alias 337 tel: URI Address-of-Record of a global E.164 number, or both. 339 It is proposed to provide the numeric userinfo in such a way that it 340 maps as partial number to the global E.164 number as defined in ITU- 341 Rec. E.164 Annex B. 343 There are two main reasons to do this: 345 1. Most VoIP terminals in use are similar to normal phone terminals 346 (or even use POTS Phones with a terminal adaptor) and provide only a 347 numeric keypad, and 349 2. if VoIP Applications are migrating from existing PBX or Centrex 350 Systems, they want to provide their users with the same environment 351 as before. 353 The task of a system administrator of such an administrative domain 354 is to set up a consistent numbering and dialing plans, leaving room 355 for future extensions and also for access codes to reach other 356 numbering plans. 358 This document tries to give advice in setting up consistent global 359 and local (private) numbering and dialing plans including access 360 codes to be used within and across administrative domains. 362 The proposed numbering and dialing plans are also compatible with 363 existing numbering and dialing plans on the PSTN/ISDN and especially 364 with the global numbering plan as defined in ITU-T Rec. E.164. The 365 proposed numbering plans can also easily implemented in ENUM for 366 routing within and between administrative domains. 368 3. Numbering and Dialing plans 370 This section explains existing numbering and dialing plans in general 371 and also some basic definitions. 373 3.1 Numbering Plans 375 A numbering plan defines the structure of a namespace consisting only 376 of strings of decimal digits. It is an inverted tree, consisting of 377 nodes, called number blocks or number ranges and of leaves, called 378 numbers. In a telecommunication numbering plan the numbers are called 379 phone numbers and uniquely identify either directly end-points in a 380 telecommunication network (e.g. a subscriber line), or indirectly 381 temporarily connected users (e.g. mobile or personal devices), or 382 also indirectly specific services (e.g. a freephone service). 384 Note for net-heads: A numbering plan is very similar to the structure 385 of the DNS. If you take an E.164 number e.g. +436644204100, the '+' 386 can be considered as the root and each single digit can be considered 387 as a label. There are only two minor and one big difference: 389 � the root and the "top level domain" is on the left side 390 � a label can be only be a single decimal digit 392 Therefore a mapping from a phone number to DNS is very easy: if one 393 swaps the order of the digits, places dots between the digits and 394 replaces '+' with 'e164.arpa', you get exactly a domain name as 395 specified in ENUM. 397 Now to the big difference: in the DNS each node may contain data, 398 e.g. it is possible to have the following e-mail addresses: 399 user@acme.com and user@dept.acme.com, because there are different MX 400 records in acme.com and dept.acme.com. 402 In a numbering plan only the leaves of the tree are phone numbers, 403 that is, they define end-points, users or services. The +43664 part 404 of a number is called a number block, or if dialed (see below), it is 405 called an incomplete number (not a partial number) and (almost) never 406 leads to a destination (with the exception of pilot numbers for PBX 407 with direct-dialing-in (DDI or DID), see below). 409 In some numbering plans also hexadecimal digits are allowed, but only 410 for internal network specific purposes and not for the normal user. 411 These digits are not considered any further here. E.164 numbers 412 consist only of decimal digits (and so do the labels in ENUM, except 413 e164.arpa) 415 End Note for net-heads. 417 As stated above, a numbering plan specifies the format and structure 418 of the numbers used within that plan. It typically consists of 419 decimal digits segmented into groups in order to identify specific 420 elements used for identification, routing and charging capabilities, 421 e.g. within the E.164 global numbering plan to identify countries, 422 national destinations, and subscribers. 424 A numbering plan does NOT include the prefixes to be dialed by the 425 calling user (this is part of the dialing plan), and it also does not 426 include suffixes and additional information required to complete a 427 call. 429 3.2 Types of Numbering Plans 431 The following types of numbering plans exist in principle: 433 � The global E.164 Numbering Plan 434 � National numbering plans 435 � Local or network specific numbering plans 436 � Private numbering plans. 438 They will be discussed below. Some additional useful terminology in 439 advance: 441 Closed and open numbering plans 443 Only the leaves of the inverted tree are phone numbers. To allow the 444 users and also the phone systems to find out if a number is complete, 445 some numbering plans define a fixed length for all numbers or at 446 least for certain numbering blocks (ranges). 448 A closed numbering plan refers to a telephone numbering scheme that 449 has a fixed number of digits, not counting special service codes. The 450 North American Numbering Plan +1 is an example for a closed numbering 451 plan, because there are always ten digits (10D) associated with each 452 national number: 3 digits area code (NPA) followed by the 7 digits of 453 the subscriber number. Australia +61 is another example of a closed 454 numbering plan. 456 Note: this term is sometimes confused with a closed dialing plan: A 457 closed dialing plan refers to a national requirement to use all 458 digits of a national number (often including a trunk prefix) to place 459 a call, whether local or long distance. End Note. 461 There are other numbering plans which have variable number length, 462 only defining the minimum and maximum length of digits, e.g. in 463 Austria the area codes may be 1 to 4 digits and the local numbers may 464 be 3 to 8 digits. This is an open numbering plan. 466 3.2.1 The Global E.164 Numbering Plan 468 This is also called the International Public Telecommunication 469 Numbering Plan according to ITU-T Rec. E.164. The numbers are called 470 International Public Telecommunications Numbers (IPTN) in the 471 international format (or E.164 numbers). 473 A number according to ITU-T Rec. E.164 is a string of decimal digits 474 that uniquely identifies a user-network interface, e.g. PSTN/ISDN or 475 mobile terminals and individuals utilizing specific global services, 476 e.g. Universal International Freephone Numbers (UIFNs). Most of the 477 services/subscribers can be addressed directly, but in cases where 478 indirect addressing is used number translation is required, e.g. for 479 UIFNs. The number contains directly or leads to the information 480 necessary to route the call to the termination point. 482 A number can be in a format determined nationally or in an 483 international format. The international format is known as the 484 International Public Telecommunication Number (often also known as 485 E.164 Number) which includes the country code and subsequent digits, 486 but not the international prefix. 488 The global E.164 Numbering Plan defines the International Public 489 Telecommunication Numbers and their structure (e.g. Country Code 490 and National (Significant) Number or Global Subscriber Number 491 ). 493 3.2.2 National Numbering Plans 495 A national numbering plan is the national implementation of the E.164 496 global numbering plan (e.g. N(S)N = National Destination Code 497 and Subscriber Number 499 3.2.3 Local or network specific Numbering Plans 501 A local or network specific numbering plan is a local or network 502 specific implementation of a national numbering plan and therefore 503 part of the E.164 numbering plan. It may not exist in some national 504 numbering plans (e.g. in closed dialing plans). 506 3.2.4 Private Numbering Plans 508 A private numbering plan is an implementation of a numbering in a 509 private telephone network. It may or may not be part of the national 510 or local numbering plan. 512 If a private numbering plan maps to the global E.164 Numbering Plan 513 the private numbers are part of the International Public 514 Telecommunication Number as partial numbers, as defined in ITU-T Rec. 515 E.164 Annex B. Only these private numbering plans are considered 516 within this document. 518 Note: The tel: URI as defined in RFC2806bis uses the terms global and 519 local number. Within RFC2806bis the term global number is used only 520 for IPTN (E.164 numbers) in the format 'tel:+43179780'. All other 521 numbers e.g. in the format 'tel:32;phone-context=+43179780' or 522 'tel:7978032;phone-context=+431 are called local numbers. Therefore 523 local numbers may be numbers from national, local or private 524 numbering plans. End Note. 526 3.2.5 Non-E.164 numbers 528 Any international number which does not conform to the structure, 529 length and uniqueness as defined ITU-T Rec. E.164 is not an E.164 530 number. Non-E.164 numbers may not be passed across any Network 531 boundaries without a specific bilateral agreement. 533 Some examples are local special numbers, network specific numbers, 534 etc. For more information see ITU-T Rec. E.164 Annex A. 536 '911' and other emergency numbers (e.g. '112' in Europe) are a 537 typical examples of non E.164 �numbers. Even if they may be dialed 538 from another country in principle, they lack the uniqueness. 540 3.3 Dialing Plans 542 A numbering plan is a name space and defines the end-points from the 543 point of the called user. Phone numbers are assigned to network-end 544 points, users or services. 546 A user normally does not enter in most cases a number in his device. 547 The user is entering a "dialing string", depending on his local 548 context. 550 A dialing plan is a string or combination of decimal digits, symbols, 551 and additional information that defines the method by which a defined 552 numbering plan is used by the calling user. A dialing plan includes 553 the use of prefixes, suffixes, and additional information, 554 supplemental to the numbering plan, required to complete the call. It 555 is therefore the method to access the given name space. 557 Depending on the mapping of the dialing plan to the numbering plan, 558 it may be necessary to leave certain number blocks of the namespace 559 of the numbering plan unused for use of prefixes (access codes) to 560 access other numbering plans or network specific services. 562 Prefix 564 A prefix is an indicator consisting of one or more digits that allow 565 the selection of different types of number formats or numbering plans 566 to be used. 568 Another type of a prefix is a Carrier Access Code (CAC) followed by a 569 Carrier Identification Code (CIC) and then the requested number 570 (eventually including again a prefix). This is used to select within 571 the originating network the carrier network to be used to route the 572 call to the destination network. This is a different type of prefix 573 and should NOT be confused with the access code to select the dialing 574 plan. 576 International Prefix 577 A digit or combination of digits used to indicate that the number 578 following is a full E.164 Number. 580 Note: A numbering plan consists only of decimal digits (with the 581 above mentioned exception of network specific hexadecimal digits). A 582 dialing plan may also consist of symbols (e.g. '+') and hexadecimal 583 digits (e.g. '*', '#', 'A-F'). Their use is up to the administrator 584 of the dialing plan. A normal user may not be able to dial all of 585 these 'digits'. End Note. 586 The symbol '+' has a special predefined meaning, originating from 587 mobile networks: If a number is preceded by a '+', the '+' has to be 588 replaced by the digits equivalent to the international prefix valid 589 within this dialing plan, e.g. '00' in most European national dialing 590 plans or '011' in the North American dialing plan. 592 Important note: The hexadecimal digits may be used '*' and '#' to 593 manipulate supplementary services and are always network-specific. 594 They should therefore only be used as prefixes to access other 595 numbering plans if it is not planned to use them for supplementary 596 services in the future. End of important note. 598 3.3.1 Types of Dialing Plans 600 A user on the PSTN/ISDN is always in one defined dialing plan at a 601 given time. That means, if he is going off-hook and starting dialing 602 digits, or if he enters the digits in his device and submits them in 603 one block, there is always ONE defined dialing plan assumed by the 604 system receiving the dialed digits (dialing string). The user has to 605 know the dialing plan in use, e.g. by reading the manual (phone 606 book). The dialing plan does never change on a device connected to a 607 phone system via a fixed line; it may change in case of a mobile 608 phone while roaming. 610 Basically the dialing plan can be 612 � private, 613 � local, 614 � network-specific or 615 � national. 617 Note that there is no global dialing plan. 619 3.3.2 Access to numbering and dialing plans 621 The basic principle of a dialing plan is a follows (although there 622 are exceptions): 624 � If you dial a number without any prefix, you are accessing a 625 number of the associated numbering plan. 627 � If you dial a prefix (access code), you are accessing another 628 numbering or dialing plan. 630 Normally the dialing plans are hierarchically, especially if the 631 numbering plans are compatible, as it is in the case of E.164 632 numbers. It is recommended by ITU to use '0' as access code for going 633 up the hierarchy, but this is not implemented in all countries 634 (mostly because for historical reasons the number range is not 635 available). 637 1. If your phone is connected to a PBX line, you dial either the 638 extension directly or an access code (e.g. '0' or '9') to access the 639 local dialing plan. If your phone is directly connected to the 640 PSTN/ISDN, goto step 2. 642 2. Now you may dial either a local number or again an access code 643 (e.g. '0') to access the national numbering or dialing plan. 645 3. There you may dial a national number or again an access code (e.g. 646 '0') to access the international numbering plan. 648 There is normally no way to go to another numbering or dialing plan 649 directly on the same hierarchy level or to go down the hierarchy. The 650 only way to access another numbering or dialing plan normally is to 651 go via the lowest common hierarchy. This requires that the other 652 numbering plan is mapped into the next higher hierarchy. To reach 653 another local numbering plan in the same country requires going via 654 the national dialing plan, to reach a local numbering plan in another 655 country requires dialing the international access code and the E.164 656 number including the country code. 658 3.3.3 Mapping of private numbering plans as partial numbers 660 To reach another private numbering plan with DDI via the PSTN/ISDN 661 requires a mapping of the private numbering plan to the E.164 662 numbering plan as partial numbers. In some cases a given private 663 number may even be reached with two or three different E.164 numbers 664 (e.g. from one or more local numbering plans, from one or more 665 national numbering plans, and here either from a mobile number or a 666 number for corporate networks. 668 The extension 3184 of a Vienna company may be reached via +43 1 60501 669 3184 (Vienna), +43 664 67070 3184 (mobile) or +43 50811 3184 670 (corporate networks). 672 3.3.4 Cross trunks or cross connections 673 In some case there may exist additional access codes to directly 674 access other numbering plans as a short cut. These access codes are 675 called cross trunks or cross connections. For technical reasons these 676 cross connections have been implemented also in the public PSTN/ISDN 677 in the past when the E.164 numbering plan was not fully implemented 678 yet. They still exist and are widely used between private networks 679 with heavy traffic relations. These cross trunks may be implemented 680 also with physical trunks or only virtually as cross connections. 681 Often numbers out of the number range '9' are used for this purpose. 683 It is depending on the system administrator of the destination 684 network if the dialing plan or only the numbering plan can be 685 accessed via these cross connections. Normally only the numbering 686 plan may be accessed and sometimes the access is even more restricted 687 to certain number ranges. The reason for the blocking of the dialing 688 plan (especially the access code to the next hierarchy) is to prevent 689 transit calls (for billing reasons). 691 Of course the number ranges (blocks) used for these access numbers 692 cannot be used within the numbering plan. Since often the number 693 range '1' is used for network-specific services, it is quite common 694 to use only the number ranges from '2' to '8' for subscriber numbers. 696 3.3.5 Closed Dialing Plans 698 In some countries and networks closed dialing plans are used. A 699 closed dialing plan refers to a national requirement to use all 700 digits of a national number (often including a trunk prefix) to place 701 a call, whether local or long distance. The current systems in France 702 (as of October 1996) and Belgium (as of January 2000) are examples of 703 closed dialing plans. 705 The issue of closed dialing plans can be somewhat confusing. Not only 706 that the terms closed dialing plan and closed numbering plan are used 707 ambiguously in literature, there are two types of closed dialing 708 plans. 710 Type I is derived by canceling the direct access to the local 711 numbering plan, but leaving the rest of the local dialing plan as is: 712 one always has to dial the national access code (e.g. '0') to reach 713 national E.164 numbers. Only network-specific numbers and service 714 code may be dialed without prefix. Examples are Switzerland and 715 France. Also many mobile networks use this type. This is less 716 logical, but easier to tell the customers: "You have to dial now the 717 area code for local numbers also." People are also used to this 718 approach from mobile phones anyway. 720 Type II is derived by canceling both the local numbering plan and 721 dialing plan: one may dial national numbers directly without a 722 prefix. One example is Portugal. This approach seems more logical and 723 also saves one digit to dial, but is harder to explain: "You have to 724 dial now the area code for local numbers also, but you must not dial 725 the national access code". To confuse things even further from a 726 logical point, but to make things easier for customers, the 727 international access code in Portugal is still '00'. 729 In the North American Numbering plan all variants exist, normally you 730 may dial 7 digits xxx-xxxx to access the local dialing plan, and 1- 731 xxx-xxx-xxxx (1+10D) to access the national dialing plan, but in some 732 NPAs you also may dial only the 10 digits. In some NPA the dialing 733 plan is closed, so you may only use 1-10D. With mobile phones you 734 also must use 1+10D always. 736 In general, the NANP is moving to 1+10D in all NPAs (for more 737 information see www.nanpa.com ). 739 4. Types of numbers in existing numbering plans 741 Phone numbers in the PSTN/ISDN serve two main purposes: to route 742 calls properly to their destination and to be able to tariff the 743 call. Before the introduction of IN-services and all-call-query (ACQ) 744 for all numbers dialed (also still today), a switching system must be 745 able to analyze the first digits dialed and deduce the routing 746 information and the tariff information. For E.164 numbers in the 747 international format this is limited to the first 7 digits. 749 It is therefore necessary to group the numbers in certain number 750 blocks to be able to derive routing and/or billing information. This 751 is also required to enable the customers to derive especially the 752 expected cost and/or service of the call by looking at the number. 754 4.1 International Public Telecommunication Numbers (E.164 Numbers) 756 The ITU-T Rec. E.164 defines the following types of International 757 Public Telecommunication Numbers (IPTN). A distinction between the 758 types of numbers can be made within the first three digits. 760 � IPTN for Geographic Areas 762 These are the "real" Country Codes (CC) and are one to three digits 763 in length. The maximum length of an IPTN is 15 digits in principle, 764 but nationally shorter length may be required (e.g. a number of the 765 NANPA has a maximum length of 11 digits). The further structure is a 766 national matter and will be discussed in the next section. 768 In order to determine the country of destination, the most 769 appropriate network routing and the proper charging, the originating 770 country must analyze a number of digits of the E.164 international 771 number (maximum of 7). The length of the National Destination Code 772 (NDC) increases the potential requirement for number analysis because 773 it provides for a combination of either a Trunk Code (TC) and/or a 774 network identification function. Careful consideration should be 775 given to the preparation of the National Destination Code (NDC) 776 assignments. 778 � IPTN for Global Services 780 The numbering plan for global services is service specific. Each use 781 of an E.164 country code for a global service needs to comply with 782 numbering assignment principles, as specified in Recommendation 783 E.190, as identified for the specific service, and the criteria and 784 procedures as specified in Recommendation E.164.1. Refer to the 785 appropriate numbering Recommendation for documentation regarding the 786 numbering scheme and any service specific principles, e.g. 787 Recommendation E.168 � Application of E.164 numbering plan for UPT. 789 The international public telecommunication number for global services 790 is composed of the 3-digit country code applied for the global 791 service and the Global Subscriber Number (GSN). The maximum length is 792 15 digits. 794 Digit analysis for global services is service specific. In order to 795 determine the specific global service, and the call routing and 796 charging, the digit analysis should not exceed 7 digits, e.g. 3-digit 797 CC + 4 digits of N(S)N. Refer to the appropriate ITU-T numbering 798 Recommendation for documentation regarding the number analysis 799 requirements for the specific global service. 801 Currently the following Global Services are defined: 803 o ITU-T Recommendation E.168 (1999), Application of E.164 numbering 804 plan for UPT. 806 o ITU-T Recommendation E.169 (1998), Application of Recommendation 807 E.164 numbering plan for universal international freephone numbers 808 for international freephone service. 810 o ITU-T Recommendation E.169.2 (2000), Application of Recommendation 811 E.164 numbering plan for universal international premium rate numbers 812 for the international premium rate service. 814 o ITU-T Recommendation E.169.3 (2000), Application of Recommendation 815 E.164 numbering plan for universal international shared cost numbers 816 for the international shared cost service. 818 � IPTN for Networks 819 International public telecommunication numbers used by Networks 820 consist of three parts: a shared 3 digit E.164 country code; an 821 identification code; and a subscriber number. The maximum length of 822 international public telecommunication numbers used by Networks is 823 fifteen (15) digits. 825 For calls utilizing the international public telecommunication number 826 for Networks, the maximum number of digits to be analyzed is seven, 827 which includes the three digits of the E.164 country code, the 828 identification code, and the initial significant digits (if any) of 829 the subscriber number. A minimum of the 3-digit country code and IC 830 must always be analyzed to determine the appropriate routing and 831 charging. 833 � IPTN for Groups of Countries 835 International public telecommunication numbers used by Groups of 836 Countries consist of three fields: a shared three digit Rec. E.164 837 Country Code; a one digit Group Identification Code; and a Subscriber 838 Number to a maximum length of eleven digits. The maximum length of 839 international public telecommunication number used by Groups of 840 Countries is fifteen digits. 842 These are the first three digits of international public 843 telecommunication number for Groups of Countries. A country code for 844 Groups of Countries is a shared (i.e., shared between GoC's) three 845 digit CC used in combination with a single digit GIC to uniquely 846 identify a Group of Countries. 848 The maximum number of digits to be analyzed for the processing of 849 calls to international public telecommunication numbers for Groups of 850 Countries is seven. This includes the CC field (three digits) plus 851 the GIC field (one digit) plus the first three digits of the 852 Subscriber Number (SN). A minimum of four digits (i.e., CC + GIC) 853 must always be analyzed to determine the appropriate routing and 854 charging. 856 4.2 National E.164 Numbers 858 Since the structure and also the types of numbers and services 859 provided are a national matter, there exists a big variety of 860 implementations, although there are some recommendations from ITU and 861 also some common international and regional approaches. 863 Note: One should consider that national numbering plans have 864 historically evolved and a complete alignment of these numbering 865 plans would cause major changes to the existing numbering plans. 866 Since these changes are very costly and causing major resistance by 867 the public, they are either avoided at all or are long term projects. 869 Even such a simple change to introduce the recommended access code 870 '0' for international calls has not been implemented globally yet. 871 The introduction of a new globally unique access code in all national 872 dialing plans (e.g. for VoIP) is absolutely impossible � don't even 873 think of it. End Note. 875 In most countries the following types of numbers have been 876 introduced. In most cases a distinction between the types of numbers 877 can be made within the first three or four digits. 878 Since the grouping or categorization differs in most countries, a new 879 and simplified grouping is proposed: 881 4.2.1 'Pure' Geographic numbers 883 These are the "original" phone numbers for fixed line end-points. In 884 open numbering plans they consist of a "trunk code � TC" or "area 885 code", giving the geographic area or region and the "subscriber 886 number � SN". The SN may be dialed in open dialing plans directly out 887 of the local dialing plan. Customers may derive the TC (and also the 888 tariff for distance) by knowing the address of the called user. 890 The TC is used to route the call to the switching system(s) serving 891 the geographic region and also to derive the tariff from the distance 892 between the originating and termination end-point. 894 In many countries local number portability is possible if the 895 customer is moving to another location within the same TC range. A 896 customer may also port these numbers to another service provider 897 without changing his location; this is called service provider 898 portability. 900 In most countries also databases are available giving the exact 901 location of the end-point e.g. for emergency services. 903 These geographic numbers are using up most of the numbering space and 904 have been the reason for earlier discussions on numbering exhaust. 905 For historic technical reasons the numbering space is not used 906 economically. Since some years the number of fixed lines using mostly 907 these geographic numbers is decreasing. 909 For this type of numbers number ranges out of each TC are assigned to 910 network operators or service providers, which in turn assign the 911 numbers to the end-users. 913 4.2.2 Non-geographic numbers for private networks 915 A range of non-geographic numbers may be used for networks private 916 networks with more then one connection to the PSTN/ISDN. These 917 connections normally have also geographic numbers assigned. These 918 numbers consist of a "national subscriber number" and can only be 919 dialed locally by accessing the national dialing plan and by 920 prefixing the national access code. The "national subscriber number" 921 consists of a pilot number for the private network (company) and a 922 mapping of the private numbering plan as partial number. 924 The "pilot" number is translated to the nearest geographic number 925 providing access to the private network and also to derive the 926 tariff. This tariff is in the most cases only dependent on the type 927 of number (the number ranges assigned for private networks), and not 928 on the pilot number. 930 For this type of numbers service provider portability is available. 932 For this type of numbers the pilot numbers are assigned to the 933 private networks, which in turn assign the partial numbers to the 934 end-users. 936 4.2.3 Non-geographic numbers for networks 938 Non-geographic number ranges may also be used for networks (e.g. 939 mobile networks). They consist in open numbering plans of a "network 940 destination code � NDC" and also a "subscriber number �SN". 942 The NDC is used to route the call to the nearest Point-of- 943 Interconnect of the network given by the NDC and also to derive the 944 tariff. The tariff may either be dependant on the type of network or 945 dependant on the specific network. 947 Between the same types of networks (e.g. mobile networks) service 948 provider portability may be available in some countries. 950 For this type of numbers NDCs are assigned to network operators or 951 service providers, which in turn assign the numbers to the end-users. 953 Note that in some countries also geographic numbers may be used for 954 mobile subscribers. End Note. 956 4.2.4 Non-geographic numbers for personal services 958 Non-geographic numbers may also be used for personal services . They 959 consist in open numbering plans of a "network destination code � NDC" 960 and also a "subscriber number �SN". 962 Depending on the implementation of the personal services, either the 963 NDC is used to route the call to the nearest Point-of-Interconnect of 964 the network providing the personal service, or the full number is 965 translated to route the call again the a PoI, or directly to the 966 geographic number where the user is currently connected to. The 967 number range is also used to derive the tariff. 969 Personal numbers are normally service provider portable by 970 definition, especially if the number is assigned directly to the end- 971 user. Number ranges may also be assigned to service providers, which 972 in turn assign the numbers to the end-users. 974 4.2.5 Non-geographic numbers for services (tariff related) 975 Non-geographic number ranges are used for services. They consist in 976 open numbering plans of a "network destination code � NDC" and also a 977 "subscriber number �SN". The NDC defines the type of service. 979 Since most of these services are related to billing, the NDC is 980 primarily used to derive the tariff. This becomes clear if we look at 981 the services in question: these are freephone, shared cost and 982 premium rate or other value added services. 984 Services may be hosted with different service providers and are also 985 translated finally to a geographic number for termination. These 986 services are normally implemented as IN-services and two IN-dips are 987 required for completion: the first to find out the network or service 988 provider hosting the service and a second to translate the service 989 number to the final destination number. This second translation may 990 be dependant on date, time and origination of the call. 992 In most case service provider portability is available, but only 993 between the same types of service. 995 This type of numbers is in most cases directly assigned to the end 996 user and then hosted by a service provider. 998 It should be noted that even if some of this services may be reached 999 uniquely by e.164 numbers, but are blocked for international incoming 1000 calls because they cannot be billed properly. 1002 4.2.6 Discussion of the existing schemes for types of numbers 1004 The boundaries between the classifications of the types of numbers 1005 are already blurred in the existing schemes and may differ in the 1006 various national implementations. 1008 Some examples (not exhaustive): 1010 Some countries assign numbers out of geographic numbering blocks for 1011 access to mobile wireless terminals e.g. in the NANP. Therefore the 1012 same tariffs are charged to calling users regardless of destination 1013 in the fixed or mobile networks and also regardless of mobile 1014 network. The mobile networks therefore may charge air-time to the 1015 called subscriber. 1017 Personal services are currently classified as non-geographic numbers 1018 in most countries and also within the global international E.164 1019 numbers. The reason for this is that existing number ranges for 1020 personal numbers are implemented as Personal Services along the 1021 service description of for Universal Personal Telecommunications 1022 (UPT) as specified in ITU-T Rec. F.85x series. The basic assumption 1023 of UPT is that an UPT user may register on any other fixed or mobile 1024 terminal and receive calls to the personal number and also may make 1025 calls from this terminal in his/her account. This requires an IN-type 1026 service with All Call Query (ACQ) to translate the dialed UPT number 1027 to the number of the line where the user is currently registered. 1028 This service is currently implemented rarely and if, only on a 1029 national scale, because there is no global interworking of IN- 1030 services available. For this reason and also because of the pricing 1031 of the service it was not very successful on the market. 1033 A global implementation using the assigned CC for UPT +878 and IP 1034 technology is under development. Although here the users may also 1035 attach to PSTN/ISDN lines, the prime intention of the service is for 1036 "mobile" users on the Internet. 1038 On the other hand, one may consider mobile numbers also as "personal" 1039 numbers and mobile services as "personal" services, because a mobile 1040 numbers are (at least in GSM and UMTS) linked to Subscriber Identity 1041 Modules (SIM). These SIMs are attached temporarily to a device (the 1042 mobile phone). The device also gets a (temporary) number (MSRN) and 1043 the routing of the call is done by this numbers. This also requires a 1044 translation of the number dialed (the mobile number) to the number 1045 assigned currently to the device, the mobile subscriber roaming 1046 number (MSRN). The MSRN is also a E.164 number but used only within 1047 or between mobile networks to route the call properly to the 1048 destination mobile switching center (MSC) of the roaming subscriber 1049 (user). The translation is also done by an IN-type service with ACQ 1050 via the home location register (HLR) of the subscriber. 1052 The technical implementations of personal and mobile numbers are very 1053 similar, with one exception: there is a globally interworking IN- 1054 service available, but only within and between the GSM/UMTS networks. 1056 Therefore one may question the classification of mobile numbers in 1057 the existing categories �geographic or non-geographic for networks 1058 (they may also be classified as type non-geographic for services) and 1059 one may also question the statement that numbering resources are 1060 allocated technology independent. 1062 It is therefore proposed to classify both personal and mobile numbers 1063 as equivalent and also as non-geographic number for networks. 1065 4.2.7 Proposed new scheme for types of numbers 1067 It is therefore proposed to use a new classification scheme: 1068 � Pure geographic numbers 1069 � Non-geographic numbers for private networks 1070 � Non-geographic numbers for networks and personal numbers 1071 (including mobile networks and personal services using VoIP networks) 1072 � or better: 1073 mobile personal services. 1074 � Non-geographic numbers for tariff related services 1076 Even if mobile (wireless) and mobile (VoIP) networks (or services) 1077 are keep distinct for some time, the may merge into one group of 1078 services, namely mobile personal services very soon, especially with 1079 so-called dual mode devices. 1081 Note: These devices are announced for the 4Q2003 and will have both 1082 GSM and WiFi (VoIP) capabilities and may even use the same SIM card 1083 for identification and authentication. End Note. 1085 4.3 Partial Numbers 1087 Private numbering plans may map part or all of their numbers to an 1088 E.164 Number in such a manner that destinations (extensions) within 1089 the private network may be reached form the public PSTN/ISDN by 1090 direct-dialing-in (DDI). This is described in more detail in ITU-T 1091 Rec. E.164Annex B "Application of international public 1092 telecommunication numbers for ISDN". 1094 This is done currently in the following way: a number block of an 1095 E.164 number is assigned to a company or provider. This numbering 1096 block is called pilot number. Then the numbering plan of the private 1097 network is attached as partial number. 1099 Pilot number and partial number together are a full E.164 number. The 1100 full E.164 number MUST fit into the national or international 1101 numbering plan, especially concerning digit length. 1103 /-----full E.164 number-----\ 1105 /--------N(S)N-------\ 1107 +----+ +-----+ +------------+ 1108 | CC | | NDC.| | SN | 1109 +----+ +-----+ +------------+ 1111 \---pilot number---/\partial/ 1112 number 1114 Types of numbers used for this purpose are: 1116 � National Geographic numbers 1117 � National non-geographic numbers for private networks 1118 � National non-geographic numbers for mobile networks 1119 � Global numbers for networks 1121 Note: If a pilot number is in a numbering range supporting number 1122 portability, only the pilot number (at the endpoint of the PSTN/ISDN) 1123 is portable. End Note. 1125 This is the reason why personal numbers should not be used for this 1126 purpose, or a distinction must be made between single portable 1127 numbers and pilot numbers. This is already the case for mobile 1128 (personal) numbers. 1130 Note: I received a comment to this section from John Elwell, stating 1131 that 1133 "In 4.3 the term "pilot number" is possibly misleading. The fact is 1134 that two private networks could have the same pilot number, e.g., one 1135 network has nnnnnn1xxx and another has nnnnnn2xxx, where pilot number 1136 nnnnnn is the same in each case. The term pilot number implies it is 1137 a kind of lead-in to a private network, but in fact it is (in such 1138 cases) insufficient to identify a particular network." 1140 To which I replied: 1141 This is a very crucial point. 1142 As you see, I copied out the picture from E.164 Annex B, which 1143 defines everything EXCEPT the pilot number (I suspect on purpose, 1144 because there seems to be no clear definition). 1146 According to your explanation, the term pilot number defines the 1147 endpoint in the public network, and I know, there may be split PRI 1148 connecting more then one PBX with different ranges. 1150 Here I have now the problem that on IP there is not really a clear 1151 definition of an "endpoint". 1153 The next problem I have is that in your example in ENUM (DNS) I could 1154 define the "endpoint" or pilot number (delegation-wise) to be nnnnnn1 1155 and nnnnnn2. The "endpoint" in the case is a change of authority and 1156 this can be in DNS only at a "point" or in numbering speak only with 1157 a full digit. If you have the case (and such cases exist) that one 1158 private network (PBX) has number ranges nnnnnn1 and 2 and the other 1159 has nnnnnn3 and 4, you could solve this in DNS only with four 1160 separate delegations, two for one network and two for the other. 1162 So if one hand the term pilot number is defined as network endpoint 1163 and this is meaningless on IP, I need another term for a point of 1164 delegation of authority in DNS. So either I come up with another term 1165 or I explicitly define in my document "pilot" number as boundary of 1166 authority to the number range holder. End of Note. 1168 4.4 Calling line identification (CLI) 1170 Phone numbers are also used to identify the identity of the calling 1171 user. For this reason the number of the calling user is transmitted 1172 as CLI to the called user. 1174 The CLI serves many different purposes: 1176 � Call-back information to the called user. 1177 � Identification of the user and his location to emergency services 1178 and legal intercept 1179 � Identification of the user for malicious call identification (MCI) 1180 � Identification of the user for accounting purposes 1182 These purposes have different requirements on the trustworthiness of 1183 the CLI. In some signaling systems two numbers may be transmitted, 1184 one un-trusted (user provided) for call back and a trusted (network 1185 provided and screened) for the other thee items. 1187 Regarding the types of numbers, in case of geo-graphic and non- 1188 geographic numbers the CLI of the user should be displayed if this 1189 user is making an originating call using this number. In case on non- 1190 geographic numbers for private networks, both numbers may be 1191 displayed if a translation is used. 1193 In case of non-geographic numbers for services either only the number 1194 of the terminating line is displayed, or also both numbers if 1195 available. 1197 The usage of CLI with VoIP and the possibility to provide secure 1198 signaling of this information via the Internet will be discussed in 1199 detail in a separate document 1201 5. E.164 Numbers for VoIP 1203 5.1 E.164 Numbers for VoIP-only 1205 In principle any E.164 number may already terminate on IP-based 1206 networks or the Internet using VoIP technology. Numbering Plans claim 1207 to be technology independent. A telecommunication network provider 1208 may claim a number range out of an area code reserved for geographic 1209 numbers or a number range out of a network destination code for 1210 (mobile) networks. Since he may use any technology within his 1211 network, he may also use VoIP technology. 1213 There are already network providers using IP technology internally 1214 (e.g. cable network providers), mobile operators are planning to use 1215 VoIP technology for UMTS. 1217 Currently these networks are mainly 'private' IP networks with no 1218 direct connection to the Internet. All interconnections with the 1219 public telephony network and to other networks are done via circuit- 1220 switched Points-of-Interconnect. All calls are routed via the PSTN, 1221 even if they originate and terminate on IP terminals. This is not 1222 efficient for various reasons, the two most important being the 1223 unnecessary double use of expensive equipment (gateways) and the 1224 reduction in Quality of Service (QoS) (delays) also caused by the 1225 unnecessary double use of gateways. 1227 Another drawback of these closed networks is that the VoIP service 1228 may only be accessed from within the networks. If users want to be 1229 mobile and use their terminal equipment anywhere on the public 1230 Internet they need to be able to connect and register on any 1231 (broadband) Internet access (e.g. via a WiFi hotspot or in a hotel or 1232 meeting broadband connection). 1234 So we have two basic requirements for VoIP: 1236 1. Calls originating on the Internet and terminating on the Internet 1237 must stay on the Internet or terminals using IP technology should be 1238 reachable via the public Internet. 1240 2. Users want to have an E.164 number independent of the PSTN, want 1241 to connect to the Internet anywhere and want to be reached via this 1242 E.164 number from anywhere, including the PSTN/ISDN. 1244 In this section the possible types of numbers for VoIP-only usage are 1245 discussed 1247 5.2 Potential E.164 Number types for VoIP-only 1249 5.2.1 National Geographic Numbers 1251 Geographic numbers have a geographic significance. A caller may 1252 determine by looking at the number the geographic region, in some 1253 countries, depending on the numbering plan even the town or village. 1254 What is even more important is that emergency services in most 1255 countries may derive from the displayed number not only the identity 1256 but also the exact location of the caller. 1258 This is considered an important feature and should therefore be 1259 implemented also for VOIP. 1261 So if geographic numbers are allocated to VoIP terminals, it should 1262 be required that the terminal can only be used at the given location. 1263 This is no technical problem e.g. with cable or xDSL access. 1265 To be more precise: it is required that the user may only register 1266 (any terminal) via the given access and make outgoing call using the 1267 geographic number in CLI from this location. 1269 This does not imply that he may not receive calls to this number 1270 anywhere in the world. This can easily be achieved via simple call 1271 forwarding to another number. 1273 Geographic numbers may either be used for residential subscribers or 1274 for private networks. In case of private networks the same is valid 1275 as stated in the next section. 1277 5.2.2 National non-geographic numbers for private networks 1279 Private networks may migrate to VoIP on their own discretion anyway. 1280 So a private network may use VoIP internally anyway. The question 1281 here is the access to the private network itself, which is done 1282 normally via the pilot number and a translation of the national non- 1283 geographic number to one or more geographic numbers. It is also up to 1284 the private network if may be reached from the Internet directly. 1286 5.2.3 National non-geographic numbers for mobile networks 1288 This is a question of definition if VoIP networks are also considered 1289 as mobile networks. 1291 One could imagine that the definition for mobile networks is extended 1292 or that there is no distinction between numbers for mobile networks 1293 and personal numbers. 1295 5.2.4 National non-geographic personal numbers 1297 This is the most convenient number range candidate to be used for 1298 mobile VoIP, because it fits the purpose best. Furthermore number 1299 range(s) for personal numbers are already reserved in most countries, 1300 but in most cases not or not extensively used. 1302 5.2.5 Global numbers for networks 1304 These numbers may be considered equivalent to national non-geographic 1305 numbers for private networks. It is up to the customer and his 1306 business if he prefers a national or global numbering resource or 1307 both. 1309 5.2.6 Global personal numbers 1310 These numbers are equivalent to national non-geographic personal 1311 numbers. It is up to the subscriber if he prefers a national or 1312 global numbering resource or both. 1314 6. How to set up numbering and dialing plans for VoIP domains 1316 6.1 Basic Requirements 1318 Note: the requirements in this section are only valid for numbering 1319 plans if the administrative domain wants to map its numbering plan to 1320 the global numbering plan and/or to a national numbering plan, to be 1321 reachable by E-164 numbers from the outside, either from the PSTN, 1322 from the Internet or both. End Note. 1324 They are only valid for dialing plans if the administrative domain 1325 wants to access the global numbering plan and/or national dialing 1326 plans to reach other administrative domains or the PSTN/ISDN via 1327 E.164 numbers. 1329 These requirements are not valid for administrative domains hosting 1330 single E.164 numbers, e.g. local numbers, mobile numbers or personal 1331 numbers requiring number portability. In this case a mapping of an 1332 own numbering plan is not required, although a dialing plan may 1333 exist. 1335 Recommendation 1: 1337 If existing numbering and dialing plans are used, e.g. if an 1338 administrative domain is migrating an existing private, local or 1339 national network to IP-technology, the numbering and dialing plans 1340 MUST be compliant to these existing numbering and dialing plans. 1342 Recommendation 2: 1344 The global numbering plan as defined in ITU-T recommendation SHALL be 1345 accessible directly and in the same way from all numbering and 1346 dialing plans defined in this document (e.g. with an international 1347 prefix). 1349 Recommendation 3: 1351 The numbering and dialing plans defined in this document SHALL be 1352 compatible with the global numbering plan as defined in ITU-T 1353 Recommendation E.164 Annex B. 1355 Recommendation 4: 1357 It SHALL be possible to address private numbers (extensions) within 1358 an administrative as defined in ITU-T Rec. E.164 Annex B.3.2 by an 1359 ISDN Number to be reached either with Direct-Dialing-In (DDI) 1360 (Overdialing) or via MSN. This implies that the private numbering 1361 plan maps to the E.164 numbers as partial numbers. Sub-addressing 1362 (network address extensions) SHALL not be used. 1364 Recommendation 5: 1366 All private numbering plans according to this document SHOULD use a 1367 fixed length of numbers. This is to allow also for fixed length E.164 1368 numbers and a defined end-of dialing for terminals. 1370 But: Note A private numbering plan could have variable number length, 1371 but the corresponding E.164 numbers are fixed length. For example: 1372 Site 1 has private numbers 77xxxx mapping to E.164 numbers +44 123 1373 4567 xxxx and site 2 has private numbers 666 xxxx mapping to E.164 1374 numbers +44 234 5678 xxxx. End Note: 1376 Recommendation 6: 1378 If the administrative domain has to be reachable from the outside, it 1379 is recommended to start setting up numbering and dialing plans first 1380 with the selection of the E.164 number range (pilot number) where the 1381 numbering plan will be mapped into as partial number. 1383 After the selection of the number range assigned to the 1384 administrative domain the according dialing plan has to be selected 1385 and defined. 1387 After the definition of the dialing plan it is known which number 1388 ranges are used up eventually for access codes, allowing defining the 1389 available numbering ranges for local numbers. 1391 6.2 Which E.164 Numbers to use for mapping of partial numbers? 1393 As stated above all types of numbers may be used for VoIP, but only 1394 certain E.164 number types are recommended for partial number mapping 1395 to administrative domains and therefore require the creation of an 1396 own numbering and dialing plan. With all other options the numbering 1397 and dialing plans are already predefined. 1399 � Global Numbers for Networks 1401 These types of numbers are recommended for administrative domains 1402 hosting subscribers from many different countries. In this case a 1403 dialing plan for global access is recommended. 1405 � National non-geographic numbers for private networks 1407 These types of numbers are recommended for administrative domains 1408 hosting subscribers from mainly this specific country. The selection 1409 is also dependent on national regulations. In this case a dialing 1410 plan for national access is recommended. 1412 � National non-geographic numbers for mobile networks 1414 These types of numbers are also recommended for administrative 1415 domains hosting subscribers from mainly this specific country. The 1416 selection is also dependent on national regulations. In this case 1417 also a dialing plan for national access is recommended. 1419 Note: this is only possible if the mobile network allows partial 1420 numbers and DDI. If the administrative domain is also mapped to 1421 another number range, it is recommended to use the dialing plan of 1422 the other numbering range and let the system convert the digits to 1423 access the mobile network. End Note. 1425 � Geographic numbers 1427 These types of numbers are recommended for administrative domains 1428 hosting subscribers from mainly this specific location (city). In 1429 this case a dialing plan for local access is recommended. 1431 Note on number assignment to administrative domains 1433 E.164 numbers may be assigned to an administrative domain in two 1434 different ways, depending on policy. 1436 1. The administrative domain is the End User 1437 2. The administrative domain is the number range holder 1439 This has implications on ENUM and Number Portability. 1441 The administrative domain is the End User 1443 In this case the administrative is equivalent to a private company 1444 implementing an IP PBX or IP Centrex. The company is the End User 1445 holding the E.164 Number minus the partial number range (also called 1446 pilot number) and has the right to opt-in into ENUM with this number. 1447 The full E.164 numbers may or may not be entered in ENUM. If the 1448 numbers are entered in ENUM, the company may in addition decide to 1449 provision the entries as a whole or give the provisioning of the 1450 single entries to the employees using the number. 1452 Number Portability never applies. 1454 Examples are administrative domains (companies) with national 1455 geographic numbers or national non-geographic numbers for private 1456 networks. 1458 The administrative domain is the number range holder 1460 This is the case the administrative domain is equivalent to a 1461 Telephony Service Provider (TSP) in the PSTN/ISDN sense. The 1462 administrative domain may now assign in turn E.164 Numbers out of the 1463 number range to End Users. 1465 In this case the End User is the holder of the E.164 Number and has 1466 the right to opt-in to ENUM on his own. 1468 If Number Portability also applies within the number range, the 1469 administrative domain must be aware of this fact and allow for 1470 porting in and out of numbers. 1472 Examples are administrative domains implementing local numbering 1473 plans as Local Exchange Carriers or administrative domains 1474 implementing service numbers e.g. personal numbers. 1476 6.3 Dialing Plans for administrative domains 1478 6.3.1 General Recommendations for all Dialing Plans 1480 These recommendations concern dialing strings and are proposals for 1481 discussion. 1483 Recommendation 7: 1485 Any dialing plan of an administrative domain SHALL recognize a global 1486 (E.164) number in the format as defined in rfc2806bis and E.123 with 1487 a leading '+'. The server of the administrative domain SHALL 1488 translate the '+' to the international access code used within this 1489 administrative domain. This is also necessary for a potential 1490 interworking with dual-mode mobile devices (e.g. GSM and WiFi), 1491 because it is common to store numbers in this format. 1493 Note: these numbers may be transmitted to the administrative domain 1494 from the user device (User agent) either in the format tel:+43179780, 1495 sip:+43179780@acme.com or h323:+43179780@acme.com. If a server 1496 receives such a request, he may either forward the call to the PSTN 1497 or launch an ENUM-query. If the result is a NAPTR with a (different) 1498 tel:+xxxx, he may launch another ENUM query. If the result of an ENUM 1499 query is the same number as the previous number queried or no NAPTR 1500 is found for this number, the call shall be forwarded to the PSTN or 1501 forwarded to another proxy with tel:+xxxx;edi (ENUM dip indicator). 1503 Recommendation 8: 1505 Any dialing plan of an administrative domain SHALL recognize the 1506 international access code either in the format '00' or '011', e.g. 1507 0043179780 or 01143179780. Only administrative domains with global 1508 access SHALL recognize both access codes. 1510 Recommendation 9: 1512 For customer convenience, the '+' character MAY be replaced by the 1513 '*' symbol, e.g. international calls MAY also be dialed *43197980. 1515 Recommendation 10: 1517 The administrative domain MAY decide to use '**' for the selection of 1518 a cross trunk or cross connection. In this case the format of the 1519 dialing string is '**yyyxxxxx' where yyy is the selection of the 1520 cross trunk to another numbering plan and xxxxx is a number of the 1521 other numbering plan selected. It is suggested to use not more then 3 1522 digits for cross trunk selection. 1524 In addition or instead of '**' also a digit MAY be used as access 1525 code for cross trunking. It is recommended to use the digit '9' for 1526 this purpose. 1528 Recommendation 11: 1530 The character '#' may be used as end-of-dial signal. 1532 The further selection of the variant of dialing plan used within an 1533 administrative domain is an internal matter, but the choice has to be 1534 communicated to the users (subscribers) 1536 6.3.2 Types of dialing plans 1538 The dialing plans for domains come in four variants: 1540 1. Dialing Plan for domains with global access 1541 2. Dialing Plans for domains with national access 1542 3. ITADs within Local Dialing plans 1543 4. Dialing Plans for domains with local access 1545 6.3.3 Dialing Plans for domains with global access 1547 This dialing plan is for administrative domains with no specifically 1548 defined local or national access. This is intended for administrative 1549 domains hosting users (subscribers) from various nationalities or 1550 countries. 1552 1. All generic recommendations from above may apply. 1554 2. All other numbers dialed are treated like private (local) numbers 1555 out of the selected numbering plan (see numbering plans below). 1557 3. Network specific numbers may be introduced in the number ranges 1 1558 and 9 (see below). 1560 As long as the problems of user location and the routing of emergency 1561 calls is not solved, it is not recommended to provide routing to 1562 national emergency services, but this may be implemented later if the 1563 numbers 112 and 911 are reserved from the beginning. 1565 6.3.4 Dialing Plans for domains with national access 1567 Administrative domains with national access will be domains using 1568 national mobile or personal ENUM numbers, where most of the users 1569 (subscribers) may come out of this country. Nevertheless, a domain 1570 may also decide to use only global access. 1572 1. All generic recommendations from above may apply, with the 1573 exception of '00' or '011'. The reason is that in this case either 1574 '00' or '011' may be valid, depending on the national dialing plan. 1576 2. Only one national access SHALL be provided. It MUST be made clear 1577 to all subscribers which national dialing plan is accessed. Example: 1578 If the Austrian national dialing plan is accessed, a number dialed as 1579 019793321 or 004319793321 is equivalent to +4319793321. 1581 3. It is up to the dialing plan administrator of the ITAD if a Type I 1582 or Type II dialing plan is selected. 1584 4. The access code to the national dialing plan depends on the 1585 national dialing plan itself, e.g. in Europe '0' is recommended, in 1586 the NANPA '1' is recommended. 1588 5. Network specific numbers may be implemented depending on the Type 1589 of dialing plan selected 1591 ITADS with national access may provide routing to national emergency 1592 services, e.g. to the European Emergency Number 112. 1594 6.3.5 Domains within Local Dialing Plans 1596 If a local dialing plan has to be implemented, the administrator has 1597 no choice. He has to implement the local dialing plan in question and 1598 also use local numbers as assigned by the numbering authority. 1600 6.3.6 Dialing Plans for domains with local access 1601 Administrative domains with local access will be domains created by 1602 migration from enterprise PBX or Centrex and therefore may already 1603 have implemented a dialing plan. In this case this dialing plan may 1604 be migrated as is to the ITAD and in most cases this means that the 1605 users are used to dial out to a local dialing plan. 1607 1. All numbers dialed starting with 0 SHALL be treated as access to 1608 ONE specific well defined local dialing plan. The numbers dialed 1609 after the 0 belong always to the local dialing plan selected. 1611 2. Only ONE local access SHALL be provided. It MUST be made clear to 1612 all subscribers which local dialing plan is accessed. Example: If the 1613 Vienna local dialing plan is accessed, a number dialed as 09793321 or 1614 0004319793321 is equivalent to +4319793321. 1616 3. Since with 0 the local dialing plan is reached, further prefixes 1617 to be used within this local dialing plan are already defined. 1619 4. All other numbers are treated like private (local) numbers. 1621 5. Network specific numbers may be introduced in the number ranges 1 1622 and 9 (see below). 1624 Domains with local access may provide routing to local emergency 1625 services, e.g. to 911, 112 or 133 in Vienna. 1627 6.4 1628 Numbering Plans for administrative domains 1630 6.4.1 General 1631 The private numbering plan is either taken over from an existing 1632 numbering plan, in case of a PBX or Centrex migration to VoIP (IP PBX 1633 or IP Centrex), or defined from scratch. It the first case it is 1634 assumed that the numbering and dialing plan is already compatible 1635 with ITU-T Rec. E.164 and proper access codes to the local or 1636 national E.164 numbering plan exists. 1638 In the second case, the following is recommended: 1640 1. Define the number of digits N of the local number. The possible 1641 number length is dependent on the E.164 number range where the local 1642 number is mapped as partial number. The minimum number of digits is 1643 the maximum will be dependant on expected final number of users and 1644 the type of E.164 number to be used to address the domain from E.164 1645 (4, 5 or even 6 digits). 1647 It should be noted that the possible flexibility may be very 1648 restricted here, especially in closed numbering plans. 1649 Example: If the number should be mapped to an E.164 number of the 1650 NANP, and only number ranges smaller then 1-xxx-xxx are assignable, 1651 the choice is between 2 to 4 digits. 1653 2. The E.164 number requested to address the administrative domain as 1654 a whole SHALL be according to ITU-T Rec E.164 Annex B.3.2 in such a 1655 way that the CC N(S)N SN or CC GSN including the private number as 1656 partial number gives a full E.164 number and does not exceed 15 1657 digits (in national numbering plans additional restrictions may 1658 apply) 1660 3. No private number SHALL start with digit 0. 1662 4. It is also recommended that no number related to a user starts 1663 with 1 and 9, so it is recommended to use the digits from 2 to 8. 1664 Therefore private numbers MAY start from e.g. 2000 to 8999. 1666 5. There is one exception from this rule. if the dialing plan is 1667 closed and of type I (which means that always an access code has to 1668 be used to dial a local number), then, depending on the access code 1669 also the ranges x0, x1 or x9 may be used for local numbers, where x 1670 is the access code. In this case all other number ranges can be used 1671 for network specific numbers. 1673 6.4.2 Network specific numbers and access numbers 1675 Administrative domains may provide network specific numbers for 1676 internal use only. This numbers SHALL not be reachable from the 1677 outside, since they are NOT E.164 numbers. 1679 A domain may decide on the use network specific numbers on its own 1680 discretion, but the following principles are recommended to be common 1681 for user convenience. 1683 Network specific numbers may be used for the following main purposes: 1684 providing internal services specific for this administrative domain 1685 and providing access to emergency services. 1687 Network specific service numbers SHALL start with digit 1 (or 9). 1689 Numbers starting with 9 may also be used as access numbers to cross 1690 connections to other domains, e.g. if an AD1 has cross connections to 1691 an AD2 and an AD3, it may decide to use access code 99 to access 1692 directly the private numbers of AD2 and 98 to access directly the 1693 private numbers to AD3. 1695 6.4.3 Emergency Numbers 1697 As long as the problems of user location and the routing of emergency 1698 calls is not solved, it is not recommended to provide routing to 1699 national emergency services from domains with global access, but this 1700 may be implemented later if the numbers 112 and 911 are reserved from 1701 the beginning. 1703 Domains with national access may provide routing to national 1704 emergency services, e.g. to the European Emergency Number 112. 1706 Domains with local access may provide routing to local emergency 1707 services, e.g. to 911 or 133 in Vienna, but only if they map to 1708 geographic numbers. 1710 6.4.4 Adress-of-Records and userinfo 1712 Subscribers of these administrative domains may be provided with the 1713 following types of Address-of-Records and alias userinfo: 1715 sip:private number@acme.com (or h323:) 1716 sip:+e164 number@acme.com (or h323:) 1717 tel:+e164 number 1719 In addition, the following types may be used within the domain: 1721 tel:;phone-context=acme.com 1722 tel:;phone-context=+e164number - partial number 1723 but these are not recommended. 1725 7. Routing of calls to E.164 numbers terminating on VoIP 1726 7.1 Routing on the PSTN 1728 In principle routing on the PSTN/ISDN is done via digit analysis. Up 1729 to seven digits may be used in a given network for this purpose. 1730 Normally the originating network (a local network e.g. a LEC) is 1731 analyzing the first digits to determine if the call is local or long 1732 distance. If it is long distance, the call is forwarded to a long- 1733 distance carrier. The long-distance carrier is again analyzing the 1734 digits, and routing the call either to the destination network 1735 (nationally) or routing the call to the country in question 1736 internationally. This is done either to another long-distance carrier 1737 or to the destination network 1739 If a number is ported, an intermediate step may be necessary to 1740 determine the final destination network. How this is done depends on 1741 the method of NP implemented and is not discussed detail here. 1742 The primary aim should be to allow for a number terminating on VoIP 1743 to be recognized via digit analysis as soon as possible. This 1744 requires the information to be in the fist 7 digits maximum. 1746 In this case the call could be routed immediately within the LEC or 1747 by the IXC to the nearest VoIP gateway. In case of E.164 numbers 1748 contained in ENUM, all such calls should be routed to the same type 1749 of gateway, namely to a gateway capable of querying ENUM (an ENUM- 1750 enabled gateway). 1752 7.1.1 National Geographic Numbers 1754 National geographic numbers will always be routed on the PSTN/ISDN 1755 network to the destination network. There is currently no way to find 1756 out on the PSTN (e.g. in the originating network) if the number 1757 terminates on VoIP (except with ACQ). 1759 7.1.2 National non-geographic numbers for private networks 1761 National non-geographic numbers for private networks will always be 1762 routed internationally to the country hosting the number. Nationally 1763 there are three options. 1765 1. The private network has a direct connection(s) to the PSTN/ISDN 1766 which is assigned a geographic number. In this case the call will 1767 routed (e.g. via IN-translation) to the nearest connection. 1769 2. The private network has no direct connection, but has a geographic 1770 number terminating on VoIP assigned. In this case the number is 1771 translated like in option 1 and then routed like a geographic number 1772 terminating on VoIP 1773 3. The private network has no direct connection to the PSTN/ISDN, but 1774 has a routing number to a gateway assigned. In this case the call 1775 will be routed to the nearest VoIP-gateway capable of routing the 1776 call further on the Internet (e.g. with ENUM). 1778 7.1.3 National non-geographic numbers for mobile networks 1780 These numbers will always be routed to the mobile network defined by 1781 the number as defined in the national network. If the "mobile" 1782 network is using VoIP technology and is assigned a separate national 1783 destination code, the call may be routed by digit analysis directly 1784 to a VoIP gateway. 1786 7.1.4 National non-geographic personal numbers 1788 If number ranges assigned for personal numbers can be assumed to 1789 terminate on VoIP, the same applies as for mobile numbers. The number 1790 range may be analyzed in the originating network and routed directly 1791 to the nearest VoIP gateway. 1793 7.1.5 Global numbers for networks 1795 In this case the routing will be very easy, because the originating 1796 network may determine the VoIP and ENUM-enabled number by the first 5 1797 digits (e.g. +882xx) 1799 7.1.6 Global personal numbers 1801 In this case the routing will be very easy, because the originating 1802 network may determine the VoIP and ENUM-enabled number by the first 5 1803 digits (e.g. +87810) 1805 7.1.7 User-ENUM and access codes 1807 In case of User ENUM (see also section �) any geographic and non- 1808 geographic number for networks could in principle terminate also on 1809 the Internet as second line service, providing the national 1810 regulation authority has opted into e164.arpa. 1812 The only question here is how a user on the PSTN may force the PSTN 1813 to make an ENUM lookup to terminate the call not on the PSTN by 1814 default. 1816 This may be done by various ways, one could be to provide a specific 1817 access code similar to a carrier selection code to route the call to 1818 a VoIP gateway. This will be a matter of the originating PSTN network 1819 and is not discussed here any further. 1821 7.2 ENUM Support for Routing of E.164 numbers on the Internet 1823 On the Internet, E.164 numbers may be routed by different means. 1824 Administrative domains may have e.g. their own translation and 1825 routing tables, but in this case the calls need to be routed on the 1826 PSTN/ISDN directly to a gateway operated by this administrative 1827 domain. Examples may be PBXes connected to the PSTN or local networks 1828 based on IP technology. 1830 To be reachable from anywhere on the Internet, a global mapping is 1831 necessary. This is provided by ENUM using the DNS. ENUM maps E.164 1832 numbers to URIs. If a domain provides URIs for its users, a mapping 1833 from any E.164 number to the given URIs is possible. 1835 For calls originating on the Internet it is of no difference if the 1836 E.164 number is also used on the PSTN or only on the Internet. The 1837 call is normally routed to the URI given in ENUM first. 1839 Only if for a given number no ENUM entry or no URI pointing to a VoIP 1840 application is found, the call may be routed to the PSTN, proper 1841 connectivity provided. 1843 7.3 Routing from Gateways and between domains with ENUM 1845 This section needs work � feedback requested. 1847 This section deals with the routing between administrative domains 1848 and also with the routing from Gateways to the destination domain. 1850 As stated above, a subscriber may have the following types of 1851 address-of-records within his domain: 1853 sip:partial-number@acme.com 1854 sip:+e164-number@acme.com 1855 tel:+e164-number 1857 Additionally he may also have as an alias an alphanumeric user(info), 1858 but this is of no concern within this document (e.g. 1860 sip:firstname.lastname@acme.com). 1862 Another user may enter either the full sip URI to access the user or 1863 dial within the domain by entering the private (partial) number 1864 directly. Outside the domain this private (partial) number alone is 1865 not meaningful and cannot be used, except with cross connections 1866 using access codes. 1868 Therefore to access a user in another domain from a given domain a 1869 sip: or h323 Address-of-Record must be used. If the user does not 1870 know Address-of-Record, or is using an IP Phone with a numeric keypad 1871 he may want to use the E.164 number instead. 1873 If the call is coming in via a Gateway, only the E.164 number is 1874 available. 1876 ENUM is providing a mapping from E.164 Numbers to sip: or h323: 1877 Address-of-Records, it is therefore proposed to use ENUM for the 1878 routing of these calls. 1880 7.3.1 The administrative domain is the End User 1882 In this case the domain has the full control over the ENUM entries. 1883 He may decide to enter only the domain of the pilot number into ENUM 1884 or to enter domains for every extension. In the latter case he may 1885 also decide to control the entries centrally by a system 1886 administrator or delegate the rights to his employees. 1888 One ENUM entry within domain of the pilot number 1890 There is a very simple way to implement a default routing to domains 1891 with ENUM: since all partial numbers are mapped in the same way to 1892 the domains main (pilot) E.164 number, one ENUM domain with the pilot 1893 E.164 number containing one wildcard NAPTR is sufficient. 1895 If e.g. OeFEG has an ENUM entry for +43 1 79780, the following entry 1896 is sufficient: 1898 $ORIGIN 0.8.7.9.7.1.3.4.e164.arpa. 1899 * IN NAPTR 10 10 "u" "E2U+voice:sip" 1900 "!^\\+4379780(.*)$!sip:\\1@sip.oefeg.at!" . 1902 to route all calls dialed including the partial numbers to this 1903 domain. 1905 ENUM entry with centralized administration 1907 If there is a centralized administration by a system administrator 1908 there could also be only one ENUM domain for the pilot number with 1909 the following entries: 1911 $ORIGIN 0.8.7.9.7.1.3.4.e164.arpa. 1912 IN NAPTR 10 10 "u" "E2U+voice:sip" "!^.*$!sip:operator@sip.oefeg.at!" 1913 . 1914 IN NAPTR 10 10 "u" "E2U+email:mailto" "!^.*$!mailto:office@oefeg.at!" 1915 . 1916 IN NAPTR 10 10 "u" "E2U+web:http" "!^.*$!http://www.oefeg.at!" . 1917 0 IN NAPTR 10 10 "u" "E2U+voice:sip" 1918 "!^.*$!sip:operator@sip.oefeg.at!" . 1920 0 IN NAPTR 10 10 "u" "E2U+email:mailto" 1921 "!^.*$!mailto:office@oefeg.at!" . 1922 2.3 IN NAPTR 10 10 "u" "E2U+voice:sip" "!^.*$!sip:32@sip.oefeg.at!" . 1923 2.3 IN NAPTR 10 10 "u" "E2U+email:mailto" 1924 "!^.*$!mailto:richard.stastny@oefeg.at!" . 1925 etc. 1927 ENUM entries with per user administration 1929 If there is a separate administration of each partial number by the 1930 employees of the company a sub-delegation to an ENUM Tier 3 Name 1931 Server operated by the company could be done. There could either be a 1932 wildcard NS Resource Record for all sub-delegations or separate NS RR 1933 for each partial number visible from the outside. 1935 $ORIGIN 0.8.7.9.7.1.3.4.e164.arpa. 1936 IN NAPTR 10 10 "u" "E2U+voice:sip" "!^.*$!sip:operator@sip.oefeg.at!" 1937 . 1938 IN NAPTR 10 10 "u" "E2U+email:mailto" "!^.*$!mailto:office@oefeg.at!" 1939 . 1940 IN NAPTR 10 10 "u" "E2U+web:http" "!^.*$!http://www.oefeg.at!" . 1941 * IN NS enumns1.oefeg.at. 1942 * IN NS enumns2.oefeg.at. 1943 oder 1944 0 IN NS enumns1.oefeg.at. 1945 0 IN NS enumns2.oefeg.at. 1946 2.3 IN NS enumns1.oefeg.at. 1947 2.3 IN NS enumns2.oefeg.at . 1948 etc. 1950 7.3.2 The administrative domain is the number range holder 1952 If the domain is hosting full E.164 numbers, the user has the right 1953 to opt-into ENUM on his own behalf and also he may have the right to 1954 port his number out of the domain regarding the telecommunication 1955 service. 1957 In this case all full E.164 numbers MUST be delegated directly from 1958 the ENUM Tier 1. 1960 But consider the following example: 1962 All numbers from the number range +8781012345 are hosted by the 1963 domain sip.nic.at 1965 All users originally are not interested in own ENUM entries and also 1966 happy with the nic.at sip service. For all this users the first NAPTR 1967 is sufficient. 1969 Now the user with the number +8781012345543210 wants to have an ENUM 1970 service but still provided by the ENUM Tier 2 Name Sever of nic.at. 1971 He gets the second NS RR. He may or may not leave his sip service 1972 within sip.nic.at. 1974 The user with the E.164 number +8781012345543211 wants to have an 1975 ENUM service, but with another ENUM Tier 2 Nameserver Provider. He 1976 gets the third NS RR. He may or may not leave his sip service within 1977 nic.at. 1979 $ORIGIN 5.4.3.2.1.0.1.8.7.8.e164.arpa. 1980 * IN NAPTR 10 10 "u" "E2U+voice:sip" 1981 "!^\\+8781012345(.*)$!sip:\\1@sip.nic.at!" . 1982 0.1.2.3.4.5 IN NS enumns1.nic.at. 1983 1.1.2.3.4.5 IN NS enumns1.otherprovider.net. 1985 8. Security Considerations 1987 This document deals primarily with routing of VoIP calls and other 1988 communications on the Internet using ENUM. Regarding the usage of 1989 ENUM and DNS technology see the security considerations in 1990 RFC2916bis. For more general aspects of privacy and security in the 1991 context of ENUM, see [7]. 1993 References 1995 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 1996 9, RFC 2026, October 1996. 1998 2 Bradner, S., "Key words for use in RFCs to Indicate Requirement 1999 Levels", BCP 14, RFC 2119, March 1997 2001 3 "The International Public Telecommunication Number Plan", ITU-T 2002 Recommendation E.164, May 1997. 2004 4 Schulzrinne H. & Vaha-Sipila A., "The tel URI for Telephone Calls", 2005 draft-iptel-rfc2806-01.txt, (work in progress), June 2003 2007 5 Faltstrom, P.& Mealling,M. "The E.164 to URI DDDS Applications", 2008 draft-ietf-enum-rfc2916bis-06.txt, (work in progress), May 2003 2010 6 "International Telephone Service", ITU-T Recommendation E.105, 2011 August 1992 2013 7 Shockey R. & Morris. J., "Privacy and Security Considerations in 2014 ENUM", draft-ietf-enum-privacy-security-01.txt, (work in 2015 progress), July 2003 2017 Acknowledgments 2019 Thanks to John Elwell for his comments. 2021 Author's Addresses 2023 Richard Stastny 2024 OeFEG 2025 Arsenal Objekt 24, Postbox 147 2026 1140 Vienna 2027 Austria 2028 Phone: +43 664 420 4100 2029 Email: richard.stastny@oefeg.at 2031 Full Copyright Statement 2033 Copyright (C) The Internet Society (2002). All Rights Reserved. 2035 This document and translations of it may be copied and furnished to 2036 others, and derivative works that comment on or otherwise explain it 2037 or assist in its implementation may be prepared, copied, published 2038 and distributed, in whole or in part, without restriction of any 2039 kind, provided that the above copyright notice and this paragraph 2040 are included on all such copies and derivative works. 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