idnits 2.17.1 draft-andreasen-sipping-rfc3603bis-04.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 19. -- Found old boilerplate from RFC 3978, Section 5.5, updated by RFC 4748 on line 1363. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 1374. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 1381. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 1387. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([RFC3261]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. -- The draft header indicates that this document obsoletes RFC3603, but the abstract doesn't seem to mention this, which it should. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust Copyright Line does not match the current year -- 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 (November 18, 2007) is 6004 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 4234 (Obsoleted by RFC 5234) ** Obsolete normative reference: RFC 4330 (Obsoleted by RFC 5905) -- Obsolete informational reference (is this intentional?): RFC 3603 (Obsoleted by RFC 5503) Summary: 4 errors (**), 0 flaws (~~), 1 warning (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SIPPING F. Andreasen 3 Internet-Draft Cisco 4 Obsoletes: 3603 (if approved) B. McKibben 5 Intended status: Informational CableLabs 6 Expires: May 21, 2008 B. Marshall 7 AT&T 8 November 18, 2007 10 Private Session Initiation Protocol (SIP) Proxy-to-Proxy Extensions for 11 Supporting the PacketCable Distributed Call Signaling Architecture 12 draft-andreasen-sipping-rfc3603bis-04 14 Status of this Memo 16 By submitting this Internet-Draft, each author represents that any 17 applicable patent or other IPR claims of which he or she is aware 18 have been or will be disclosed, and any of which he or she becomes 19 aware will be disclosed, in accordance with Section 6 of BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF), its areas, and its working groups. Note that 23 other groups may also distribute working documents as Internet- 24 Drafts. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 The list of current Internet-Drafts can be accessed at 32 http://www.ietf.org/ietf/1id-abstracts.txt. 34 The list of Internet-Draft Shadow Directories can be accessed at 35 http://www.ietf.org/shadow.html. 37 This Internet-Draft will expire on May 21, 2008. 39 Copyright Notice 41 Copyright (C) The IETF Trust (2007). 43 Abstract 45 In order to deploy a residential telephone service at very large 46 scale across different domains, it is necessary for trusted elements 47 owned by different service providers to exchange trusted information 48 that conveys customer-specific information and expectations about the 49 parties involved in the call. This document describes private 50 extensions to the Session Initiation Protocol (SIP) [RFC3261] for 51 supporting the exchange of customer information and billing 52 information between trusted entities in the PacketCable Distributed 53 Call Signaling Architecture. These extensions provide mechanisms for 54 access network coordination to prevent theft of service, customer 55 originated trace of harassing calls, support for operator services 56 and emergency services, and support for various other regulatory 57 issues. The use of the extensions is only applicable within closed 58 administrative domains, or among federations of administrative 59 domains with previously agreed-upon policies where coordination of 60 charging and other functions is required. 62 Table of Contents 64 1. Applicability Statement . . . . . . . . . . . . . . . . . . . 5 65 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6 66 3. Trust Boundary . . . . . . . . . . . . . . . . . . . . . . . . 8 67 4. Conventions used in this document . . . . . . . . . . . . . . 9 68 5. P-DCS-TRACE-PARTY-ID . . . . . . . . . . . . . . . . . . . . . 10 69 5.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 10 70 5.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 11 71 5.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 11 72 5.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 12 73 5.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 12 74 5.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 12 75 5.6.1. Procedures at Originating Proxy . . . . . . . . . . . 12 76 5.6.2. Procedures at Terminating Proxy . . . . . . . . . . . 13 77 6. P-DCS-OSPS . . . . . . . . . . . . . . . . . . . . . . . . . . 14 78 6.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 14 79 6.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 15 80 6.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 15 81 6.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 15 82 6.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 16 83 6.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 16 84 7. P-DCS-BILLING-INFO . . . . . . . . . . . . . . . . . . . . . . 17 85 7.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 18 86 7.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 20 87 7.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 21 88 7.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 21 89 7.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 21 90 7.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 22 91 7.6.1. Procedures at Originating Proxy . . . . . . . . . . . 22 92 7.6.2. Procedures at Terminating Proxy . . . . . . . . . . . 23 93 7.6.3. Procedures at Tandem Proxy . . . . . . . . . . . . . . 24 94 8. P-DCS-LAES and P-DCS-REDIRECT . . . . . . . . . . . . . . . . 25 95 8.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 25 96 8.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 27 97 8.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 27 98 8.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 28 99 8.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 28 100 8.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 28 101 8.6.1. Procedures at Originating Proxy . . . . . . . . . . . 29 102 8.6.2. Procedures at Terminating Proxy . . . . . . . . . . . 30 103 9. Security Considerations . . . . . . . . . . . . . . . . . . . 32 104 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 105 11. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 34 106 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 35 107 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36 108 13.1. Normative References . . . . . . . . . . . . . . . . . . . 36 109 13.2. Informative References . . . . . . . . . . . . . . . . . . 36 111 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38 112 Intellectual Property and Copyright Statements . . . . . . . . . . 39 114 1. Applicability Statement 116 The SIP extensions described in this document make certain 117 assumptions regarding network topology, linkage between SIP and lower 118 layers, and the availability of transitive trust. These assumptions 119 are generally not applicable in the Internet as a whole. The use of 120 these headers is only applicable within closed administrative 121 domains, or among federations of administrative domains with 122 previously agreed-upon policies where coordination of charging and 123 other functions is required, as in for example the architecture 124 presented in [DCSARCH]. Use outside such a domain could result in 125 the leakage of potentially sensitive or private information. User 126 consent to the privacy implications of the policies in [DCSARCH] is 127 strongly encouraged in those domains as well. 129 Although [RFC2119] language is used in this document, the scope of 130 the normative language is only for the area of applicability of the 131 document and, like the technology, it does not apply to the general 132 Internet. 134 2. Introduction 136 In order to deploy a SIP-based [RFC3261] residential telephone 137 service at very large scale across different domains, it is necessary 138 for trusted elements owned by different service providers to exchange 139 trusted information that conveys billing information and expectations 140 about the parties involved in the call. 142 There are many billing models used in deriving revenue from telephony 143 services today. Charging for telephony services is tightly coupled 144 to the use of network resources. It is outside the scope of this 145 document to discuss the details of these numerous and varying 146 methods. 148 A key motivating principle of the DCS architecture described in 149 [DCSARCH] is the need for network service providers to be able to 150 control and monitor network resources; revenue may be derived from 151 the usage of these resources as well as from the delivery of enhanced 152 services such as telephony. Furthermore, the DCS architecture 153 recognizes the need for coordination between call signaling and 154 resource management. This coordination ensures that users are 155 authenticated and authorized before receiving access to network 156 resources and billable enhanced services. 158 DCS Proxies, as defined in [DCSARCH], have access to subscriber 159 information and act as policy decision points and trusted 160 intermediaries along the call signaling path. Edge routers provide 161 the network connectivity and resource policy enforcement mechanism 162 and also capture and report network connectivity and resource usage 163 information. Edge routers need to be given billing information that 164 can be logged with Record Keeping or Billing servers. The DCS Proxy, 165 as a central point of coordination between call signaling and 166 resource management, can provide this information based on the 167 authenticated identity of the calling and called parties. Since 168 there is a trust relationship among DCS Proxies, they can be relied 169 upon to exchange trusted billing information pertaining to the 170 parties involved in a call. See [DCSARCH] for a description of the 171 trust boundary and trusted versus untrusted entities. 173 For these reasons, it is appropriate to consider defining SIP header 174 extensions to allow DCS Proxies to exchange information during call 175 setup. It is the intent that the extensions would only appear on 176 trusted network segments, should be inserted upon entering a trusted 177 network region, and removed before leaving trusted network segments. 179 Significant amounts of information are retrieved by an originating 180 DCS Proxy in its handling of a connection setup request from a user 181 agent. Such information includes location information about the 182 subscriber (essential for emergency services calls), billing 183 information, and station information (e.g., coin operated phone). In 184 addition, while translating the destination number, information such 185 as the local-number-portability office code is obtained and will be 186 needed by all other proxies handling this call. 188 For Usage Accounting records, it is necessary to have an identifier 189 that can be associated with all the event records produced for the 190 call. The SIP Call-ID header field cannot be used as such an 191 identifier since it is selected by the originating user agent, and 192 may not be unique among all past calls as well as current calls. 193 Further, since this identifier is to be used by the service provider, 194 it should be chosen in a manner and in a format that meets the 195 service provider's needs. 197 Billing information may not necessarily be unique for each user 198 (consider the case of calls from an office all billed to the same 199 account). Billing information may not necessarily be identical for 200 all calls made by a single user (consider prepaid calls, credit card 201 calls, collect calls, etc). It is therefore necessary to carry 202 billing information separate from the calling and called party 203 identification. Furthermore, some billing models call for split- 204 charging where multiple entities are billed for portions of the call. 206 The addition of a SIP General Header Field allows for the capture of 207 billing information and billing identification for the duration of 208 the call. 210 It is the intent that the billing extensions would only appear on 211 trusted network segments, and MAY be inserted by a DCS Proxy in 212 INVITE and REFER requests and INVITE responses in a trusted network 213 segment, and removed before leaving trusted network segments. 215 In addition to support for billing, current residential telephone 216 service includes the need for customer originated trace (of harassing 217 or obscene calls), for operator services such as busy line 218 verification and emergency interrupt (initiated by an operator from 219 an Operator Services Position System (OSPS)), for emergency services 220 such as 9-1-1 calls to a Public Service Access Point (PSAP) and the 221 subsequent call handling, and support for Electronic Surveillance and 222 Law Enforcement access as required by applicable legislation and 223 court orders. In all of these cases, additional information about 224 the call and about the subscribers involved in the call needs to be 225 exchanged between the proxies. 227 3. Trust Boundary 229 The DCS architecture [DCSARCH] defines a trust boundary around the 230 various systems and servers that are owned, operated by, and/or 231 controlled by the service provider. These trusted systems include 232 the proxies and various servers such as bridge servers, voicemail 233 servers, announcement servers, etc. Outside of the trust boundary 234 lie the customer premises equipment, and various application and 235 media servers operated by third-party service providers. 237 Certain subscriber-specific information, such as billing and 238 accounting information, stays within the trust boundary. Other 239 subscriber-specific information, such as endpoint identity, may be 240 presented to untrusted endpoints or may be withheld based on 241 subscriber profiles. 243 The User Agent (UA) may be either within the trust boundary or 244 outside the trust boundary, depending on exactly what function is 245 being performed and exactly how it is being performed. Accordingly, 246 the procedures followed by a User Agent are different depending on 247 whether the UA is within the trust boundary or outside the trust 248 boundary. 250 The following sections giving procedures for User Agents therefore 251 are subdivided into trusted user agents and untrusted user agents. 253 4. Conventions used in this document 255 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 256 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 257 document are to be interpreted as described in BCP 14, [RFC2119]. 259 The term "private-URL" used in this document refers to a SIP URI that 260 is generated by a proxy, contains a "hostport" that identifies the 261 proxy, and contains a "userinfo" string that is generated by the 262 proxy. The "userinfo" typically contains (or points to) information 263 that is not to be disclosed outside the trusted domain of the 264 proxies, such as billing account numbers, electronic surveillance 265 indication, electronic surveillance parameters, and call redirection 266 information. Consequently, the information is either stored locally 267 by the proxy, or encrypted with a private key known only to the proxy 268 and encoded in a character string in the "userinfo" portion of the 269 URL. A checksum is included in the "userinfo" data to detect 270 tampering. The mechanism by which a proxy recognizes a "userinfo" as 271 a private-URL and decodes and recovers the original information is 272 local to the proxy and is not subject to standardization. Some 273 possible implementations include an initial magic cookie (e.g., 274 z9hG4Bk followed by the pointer/information), or use of a reserved 275 "user" name (e.g., "private") with the optional "password" containing 276 the pointer/information. 278 5. P-DCS-TRACE-PARTY-ID 280 In the telephone network, calling identity information is used to 281 support regulatory requirements such as the Customer Originated Trace 282 service, which provide the called party with the ability to report 283 obscene or harassing phone calls to law enforcement. This service is 284 provided independently of caller-id, and works even if the caller 285 requested anonymity. The calling party is here identified as the 286 station originating the call. In order for this service to be 287 dependable, the called party must be able to trust that the calling 288 identity information being presented is valid. One way to achieve 289 this is described in [RFC3325]. 291 To initiate a customer-originated-trace from an untrusted UAC, an 292 additional header is defined for the INVITE request. This header is 293 called P-DCS-Trace-Party-ID, and does not appear in any other request 294 or response. The untrusted UAC also includes the Target-Dialog 295 header field defined in [RFC4538] in the INVITE request in order to 296 explicitly identify the call to be traced. The entity addressed by 297 the Request-URI performs the service-provider-specific functions of 298 recording and reporting the caller identity in the 299 P-DCS-Trace-Party-ID for law enforcement action. It then forwards 300 the call to either an announcement server or to the service- 301 provider's business office to collect further information about the 302 complaint. A trusted UAC does not use this header, as it initiates 303 this action locally. 305 5.1. Syntax 307 The ABNF description of this header is (some terms used in this ABNF 308 are defined in [RFC3261]): 310 P-DCS-Trace-Party-ID = "P-DCS-Trace-Party-ID" HCOLON name-addr 312 The ABNF production for name-addr in [RFC3261] includes uri- 313 parameters, which allows for additional parameters to be defined 314 (other-param). We here define the following other-param parameters 315 to be used with P-DCS-Trace-Party-ID: 317 timestamp-param = "timestamp=" 1*DIGIT ["." 1*DIGIT] 319 This document adds the following entry to Table 2 of [RFC3261]: 321 Header field where proxy ACK BYE CAN INV OPT REG PUB 322 ------------ ----- ----- --- --- --- --- --- --- --- 323 P-DCS-Trace-Party-ID R dr - - - o - - - 324 SUB NOT REF INF UPD PRA MSG 325 --- --- --- --- --- --- --- 326 - - - - - - - 328 The addr-spec contained in name-addr contains a URL that identifies 329 the remote endpoint. Addr-spec typically contains a tel: URL or SIP 330 URI giving the identity of the remote endpoint, as provided in the 331 signaling messages that established the session to be traced. 333 The timestamp-param contains the value of the time the UA determines 334 it received the session initiation request of the call requested to 335 be traced. The timestamp-param is populated using format defined by 336 the Simple Network Time Protocol in [RFC4330]. 338 An example of the P-DCS-Trace-Party-ID header is shown as follows: 340 P-DCS-Trace-Party-ID: sip:+12345678912@domain.com; user=phone; 341 timestamp=123456789 343 5.2. Procedures at an Untrusted User Agent Client (UAC) 345 The UAC MUST insert a P-DCS-Trace-Party-ID header into the initial 346 INVITE message for a customer-originated-trace request. The UAC MUST 347 use a SIP URI in the Request-URI with userinfo set to "call-trace" 348 and hostport identifying the call tracing entity for the untrusted 349 UA. The [RFC3603] version of the P-DCS-Trace-Party-ID did not 350 include the timestamp-param parameter, however the syntax is 351 backwards compatible with [RFC3603]. A UAC compliant to this updated 352 specification MUST insert the timestamp and the Target-Dialog header 353 defined in [RFC4538] if known to the UAC. 355 5.3. Procedures at a Trusted User Agent Client (UAC) 357 A trusted UAC performs the customer-originated-trace in a manner 358 similar to the trusted UAS, described below. A trusted UAC MUST NOT 359 include this header in any request. 361 5.4. Procedures at an Untrusted User Agent Server (UAS) 363 This header MUST NOT appear in any response sent by a UAS. 365 5.5. Procedures at a Trusted User Agent Server (UAS) 367 If the P-DCS-Trace-Party-ID header is present in the initial INVITE 368 request from a UAC, and the Request-URI of the INVITE has userinfo 369 set to "call-trace" and hostport set to the UAS, the UAS MUST perform 370 the service-provider-specific functions of recording and reporting 371 the caller identity and associated trace parameters (if any) from the 372 Target-Dialog header for law enforcement action. The UAS then MUST 373 redirect the call, via a 3xx response, to either an announcement 374 server or to the service-provider's business office to collect 375 further information about the complaint. 377 This header MUST NOT appear in any response sent by a UAS. 379 5.6. Procedures at Proxy 381 Two sets of proxy procedures are defined: (1) the procedures at an 382 originating proxy, and (2) the procedures at a terminating proxy. 383 The originating proxy is a proxy that received the INVITE request 384 from a non-trusted endpoint. 386 The terminating proxy is a proxy that sends the INVITE request to a 387 non-trusted endpoint. 389 A proxy that both receives the INVITE request from an untrusted 390 endpoint, and sends the INVITE request to an untrusted endpoint, 391 performs both sets of procedures. 393 5.6.1. Procedures at Originating Proxy 395 If the P-DCS-Trace-Party-ID header is present in the initial INVITE 396 request from the UAC, and the Request-URI of the INVITE has userinfo 397 other than "call-trace" and hostport set to other than a potentially 398 provisioned call tracing entity, then the Proxy MAY reject the 399 request, or MAY remove the P-DCS-Trace-Party-ID header from the 400 request. If the header is present in a valid request, and contains a 401 private-URL that identifies the Proxy in the hostport, then the 402 Originating Proxy SHOULD replace the private-URL with its original 403 contents (i.e., the verified identity of the caller of the session 404 that is being traced and trace parameters from the Target-Dialog 405 headers defined in [RFC4538]). 407 5.6.2. Procedures at Terminating Proxy 409 This header MUST NOT appear in any request or response sent by a 410 terminating proxy to an untrusted endpoint. 412 6. P-DCS-OSPS 414 Some calls have special call processing requirements that may not be 415 satisfied by normal user agent call processing. For example, when a 416 user is engaged in a call and another call arrives, such a call might 417 be rejected with a busy indication. However, some PSTN operator 418 services require special call processing. In particular, the Busy 419 Line Verification (BLV) and Emergency Interrupt (EI) services 420 initiated by an operator from an Operator Services Position System 421 (OSPS) on the PSTN network have such a need. Similarly, emergency 422 calls to a 9-1-1 Public Service Access Point (PSAP) may result in 423 trunk signaling causing operator ringback using a howling tone or 424 sustained ring on the originating line (country-specific variations 425 may exist). 427 In order to inform the SIP user agent that special treatment should 428 be given to a call, we use a new P-DCS-OSPS header field, which may 429 be set to a value indicating when a special type of call processing 430 is requested. We define three values in this header, namely "BLV" 431 for busy line verification, "EI" for emergency interrupt, and "RING" 432 for operator ringback (e.g., howling/sustained tone ring in the US). 434 If the user agent decides to honor such a request, the response of 435 the user agent to an INVITE with either "BLV" or "EI" will not be a 436 busy indication. Since "EI" and "RING" only occur on established 437 dialogs, they may also appear in UPDATE requests. 439 6.1. Syntax 441 The ABNF description of the P-DCS-OSPS header is as follows (some 442 terms used in this ABNF are defined in [RFC3261]): 444 P-DCS-OSPS = "P-DCS-OSPS" HCOLON OSPS-Tag 445 OSPS-Tag = "BLV" / "EI" / "RING" / token 447 This document adds the following entry to Table 2 of [RFC3261]: 449 Header field where proxy ACK BYE CAN INV OPT REG PUB 450 ------------ ----- ----- --- --- --- --- --- --- --- 451 P-DCS-OSPS R dr - - - o - - - 452 SUB NOT REF INF UPD PRA MSG 453 --- --- --- --- --- --- --- 454 - - - - o - - 456 The OSPS-Tag value of "token" is defined for extensibility, and is 457 reserved for future use. 459 6.2. Procedures at an Untrusted User Agent Client (UAC) 461 The P-DCS-OSPS header MUST NOT be sent in a request from an untrusted 462 UAC. 464 6.3. Procedures at a Trusted User Agent Client (UAC) 466 This header is typically only inserted by a Media Gateway Controller 467 [DCSARCH] that is controlling a Media Gateway with special trunks to 468 a PSTN OSPS system or PSAP. This trunk group is usually referred to 469 as a BLV-trunk group and employs special signaling procedures that 470 prevent inadvertent use. Calls originating at the PSTN OSPS system 471 are sent over this trunk group, and result in an INVITE request with 472 the P-DCS-OSPS header. 474 This header MAY be sent in an INVITE request, and MUST NOT appear in 475 any message other than those listed below. 477 OSPS-Tag value "BLV" MUST NOT appear in any request other than an 478 initial INVITE request establishing a new dialog. 480 OSPS-Tag value "EI" MUST NOT appear in any request or response other 481 than (1) a subsequent INVITE within a pre-existing dialog established 482 with the OSPS-Tag value of "BLV", or (2) an UPDATE request within a 483 pre-existing dialog established with the OSPS-Tag value of "BLV". 485 OSPS-Tag value "RING" MUST NOT appear in any request or response 486 other than (1) a subsequent INVITE within a pre-existing dialog 487 established by a UAC to an operator or PSAP, or (2) an UPDATE request 488 within a pre-existing dialog established by a UAC to an operator or 489 PSAP. 491 6.4. Procedures at an Untrusted User Agent Server (UAS) 493 If the UAS receives an INVITE request with an OSPS-Tag of "BLV", 494 dialog identification that matches an existing dialog, it MUST reject 495 the request with a 403-Forbidden error code. 497 If the UAS receives an INVITE/UPDATE request with an OSPS-Tag value 498 of "EI" or "RING", with dialog identification that does not match an 499 existing dialog which was established with the OSPS-Tag value of 500 "BLV", it MUST reject the request with a 403-Forbidden response code. 502 If the UAS receives an INVITE that contains an OSPS-Tag value of 503 "BLV" and is not willing to cooperate in offering this service, it 504 MUST reject the request with a 403-Forbidden response code. 506 The UAS SHOULD NOT reject an INVITE with a BLV OSPS-Tag due to a busy 507 condition. The UAS MUST NOT respond with a 3xx-Redirect response 508 code to an INVITE with a BLV OSPS-Tag. The UAS SHOULD NOT alert the 509 user of the incoming call attempt if the BLV OSPS-Tag is present in 510 the INVITE. 512 If an INVITE with OSPS-Tag of "BLV" is accepted (e.g., meeting all 513 QoS pre-conditions, etc.), the UAS MUST send an audio stream on this 514 connection to the address and port given in the SDP of the INVITE. 515 The UAS MAY perform a mixing operation between the two ends of an 516 existing active call and send the resulting media stream to the 517 address and port indicated. Alternatively, the UAS MAY send a copy 518 of the local voice stream, and (if no activity on the local voice 519 stream) send a copy of the received voice stream of an existing call. 520 If the state of the UAS is idle, the UAS SHOULD send a stream of 521 silence packets to OSPS. If the state of the UAS is ringing or 522 ringback, the UAS SHOULD send a ringback stream to OSPS. 524 If an INVITE/UPDATE with OSPS-Tag of "EI" is accepted, the UAS MUST 525 enable communication between the UAC and the local user. The UAS MAY 526 put any existing call on hold, or initiate an ad-hoc conference. 528 If an INVITE/UPDATE with OSPS-Tag of "RING" is accepted, the UAS MUST 529 perform operator ringback in accordance with local procedures, e.g., 530 generate a 3-second howling tone or a sustained ring, depending on 531 the state of the user equipment. 533 6.5. Procedures at a Trusted User Agent Server (UAS) 535 The procedures at a trusted UAS MUST be identical to those described 536 in 6.4. 538 6.6. Procedures at Proxy 540 In the DCS architecture, the OSPS is considered a trusted UAC. If a 541 proxy receives a P-DCS-OSPS header in a request from an untrusted 542 source, it MUST either remove the header or reject the request with a 543 403-Forbidden response. 545 A proxy that implements a call-forwarding service MUST NOT respond to 546 an INVITE request with a 3xx response, if the request contained the 547 P-DCS-OSPS header. 549 7. P-DCS-BILLING-INFO 551 There are many billing models used in deriving revenue from telephony 552 services today. Charging for telephony services is tightly coupled 553 to the use of network resources. It is outside the scope of this 554 document to discuss the details of these numerous and varying 555 methods. 557 Proxies have access to subscriber information and act as policy 558 decision points and trusted intermediaries along the call signaling 559 path. Edge routers provide the network connection and resource 560 policy enforcement mechanism and also capture and report network 561 connection and resource usage information. Edge routers need to be 562 given billing information that can be logged with Record Keeping or 563 Billing servers. The proxy, as a central point of coordination 564 between call signaling and resource management, can provide this 565 information based on the authenticated identity of the calling and 566 called parties. Since there is a trust relationship among proxies, 567 they can be relied upon to exchange trusted billing information 568 pertaining to the parties involved in a call. 570 For Usage Accounting records, it is necessary to have an identifier 571 that can be associated with all the event records produced for the 572 call. The SIP Call-ID header field cannot be used as such an 573 identifier since it is selected by the originating user agent, and 574 may not be unique among all past calls as well as current calls. 575 Further, since this identifier is to be used by the service provider, 576 it should be chosen in a manner and in a format that meets the 577 service provider's needs. 579 Billing information may not necessarily be unique for each user 580 (consider the case of calls from an office all billed to the same 581 account). Billing information may not necessarily be identical for 582 all calls made by a single user (consider prepaid calls, credit card 583 calls, collect calls, etc). It is therefore necessary to carry 584 billing information separate from the calling and called party 585 identification. Furthermore, some billing models call for split- 586 charging where multiple entities are billed for portions of the call. 588 The addition of a SIP General Header Field allows for the capture of 589 billing information and billing identification for the duration of 590 the call. 592 It is the intent that the billing extensions would only appear on 593 trusted network segments, and MAY be inserted by a proxy or trusted 594 UA in INVITE and SUBSCRIBE requests in a trusted network segment, and 595 removed before leaving trusted network segments. The P-DCS-Billing- 596 Info header extension is used only on requests and responses between 597 proxies and trusted User Agents. It is never sent to, nor sent by, 598 an untrusted UA. 600 7.1. Syntax 602 The DCS-Billing-Info header is defined by the following ABNF (some 603 terms used in this ABNF are defined in [RFC3261]): 605 P-DCS-Billing-Info = "P-DCS-Billing-Info" HCOLON 606 Billing-Correlation-ID "/" FEID 607 *(SEMI Billing-Info-param) 608 Billing-Correlation-ID = 1*48(HEXDIG) 609 FEID = 1*16(HEXDIG) "@" host 610 Billing-Info-param = RKS-Group-ID-param / Charge-param / 611 Calling-param / Called-param / 612 Routing-param / Loc-Routing-param / 613 JIP-param / generic-param 614 RKS-Group-ID-param = "rksgroup" EQUAL RKS-Group-ID 615 RKS-Group-ID = token 616 Charge-param = "charge" EQUAL Acct-Charge-URI 617 Acct-Charge-URI = LDQUOT addr-spec RDQUOT 618 Calling-param = "calling" EQUAL Acct-Calling-URI 619 Acct-Calling-URI = LDQUOT addr-spec RDQUOT 620 Called-param = "called" EQUAL Acct-Called-URI 621 Acct-Called-URI = LDQUOT addr-spec RDQUOT 622 Routing-param = "routing" EQUAL Acct-Routing-URI 623 Acct-Routing-URI = LDQUOT addr-spec RDQUOT 624 Loc-Routing-param = "locroute" EQUAL Acct-Loc-Routing-URI 625 Acct-Loc-Routing-URI = LDQUOT addr-spec RDQUOT 626 JIP-param = "jip" EQUAL jip 627 jip = LDQUOT 1*phonedigit-hex jip-context RDQUOT 628 jip-context = ";jip-context=" jip-descriptor 629 jip-descriptor = global-hex-digits 630 global-hex-digits = "+" 1*3(phonedigit) *phonedigit-hex 631 phonedigit = DIGIT / [ visual-separator ] 632 phonedigit-hex = HEXDIG / "*" / "#" / [ visual-separator ] 633 visual-separator = "-" / "." / "(" / ")" 635 This document adds the following entry to Table 2 of [RFC3261]: 637 Header field where proxy ACK BYE CAN INV OPT REG PUB 638 ------------ ----- ----- --- --- --- --- --- --- --- 639 P-DCS-Billing-Info admr - - - o - - - 641 SUB NOT REF INF UPD PRA MSG 642 --- --- --- --- --- --- --- 643 - - - - - - - 645 The P-DCS-Billing-Info extension contains an identifier that can be 646 used by an event recorder to associate multiple usage records, 647 possibly from different sources, with a billable account. It further 648 contains the subscriber account information, and other information 649 necessary for accurate billing of the service. This header is only 650 used between proxies and trusted User Agents. 652 The Billing-Correlation-ID is specified in [PCEM] as a 24-byte binary 653 structure, containing 4 bytes of NTP timestamp, 8 bytes of the unique 654 identifier of the network element that generated the ID, 8 bytes 655 giving the time zone, and 4 bytes of monotonically increasing 656 sequence number at that network element. This identifier is chosen 657 to be globally unique within the system for a window of several 658 months. This MUST be encoded in the P-DCS-Billing-Info header as a 659 hexadecimal string of up to 48 characters. Leading zeroes MAY be 660 suppressed. 662 The Financial-Entity-ID (FEID) is specified in [PCEM] as an 8-byte 663 structure, containing the financial identifier for that domain, 664 followed by a domain name. FEID can be associated with a type of 665 service and could be assigned to multiple domains by the same 666 provider. A domain could contain multiple assigned FEIDs. This 8- 667 byte structure MUST be encoded in the P-DCS-Billing-Info header as a 668 hexadecimal string of up to 16 characters. Trailing zeroes MAY be 669 suppressed. "Host" contains the domain name. 671 The RKS-Group-ID specifies a record keeping server (or group of 672 cooperating servers) for event messages relating to this call. It is 673 used to control certain optimizations of procedures when multiple 674 event message streams are being sent to the same Record Keeping 675 Server. 677 Additional parameters contain the information needed for generation 678 of event message records. Acct-Charge-URI, Acct-Calling-URI, Acct- 679 Called-URI, Acct-Routing-URI, and Acct-Loc-Routing-URI are each 680 defined as URLs; they should all contain tel: URLs with E.164 681 formatted addresses. These fields are further defined in [PCEM] 682 under the element identifiers "Charge_Number" (element ID 16), 683 "Calling_Party_Number" (element ID 4), "Called_Party_Number" (element 684 ID 5), "Routing Number" (element ID 25), and 685 "Location_Routing_Number" (element ID 22). 687 The JIP-param contains the calling jurisdiction information, or 688 numbering plan area, of the network in which the call originated. 689 The field is further defined in [PCEM] under the element identifier 690 "Jurisdiction_Information_Parameter" (element ID 82). An older 691 [RFC3603] compliant implementation may not use the JIP-param. 693 7.2. Procedures at an Untrusted User Agent Client (UAC) 695 This header is never sent to an untrusted UAC, and is never sent by 696 an untrusted UAC. 698 7.3. Procedures at a Trusted User Agent Client (UAC) 700 The UAC MUST generate the Billing-Correlation-ID for the call, and 701 insert it into the P-DCS-Billing-Info header in the initial INVITE or 702 SUBSCRIBE message sent to the terminating entity, along with the 703 charging information for the call. The UAC MUST include its FEID, 704 and the RKS-Group-ID for the Record-Keeping-Server being used by the 705 UAC. If the UAC performed a Local Number Portability (LNP) query, it 706 MUST include the Routing Number and Location Routing Number returned 707 by the query. If available to the UAC, the UAC MUST include the JIP- 708 param. 710 If the response to the initial INVITE is a 3xx-Redirect, the UAC 711 generates a new initial INVITE request to the destination specified 712 in the Contact: header, as per standard SIP. If a UAC receives a 713 3xx-Redirect response to an initial INVITE, the new INVITE generated 714 by the UAC MUST contain the P-DCS-Billing-Info header values from the 715 3xx- Redirect response. If the UAC is acting as a B2BUA, instead of 716 generating a new INVITE it MAY generate a private-URL and place it in 717 the Contact header of a 3xx-Redirect response sent to the originating 718 endpoint. This private-URL MUST contain (or contain a pointer to) 719 the P-DCS-Billing-Info value, which indicates the charging 720 arrangement for the new call, and an expiration time very shortly in 721 the future, to limit the ability of the originator to re-use this 722 private-URL for multiple calls. 724 A UAC that includes a Refer-to header in a REFER request MUST include 725 a P-DCS-Billing-Info header in the Refer-to's URL. This P-DCS- 726 Billing-Info header MUST include the accounting information of the 727 initiator of the REFER. 729 7.4. Procedures at an Untrusted User Agent Server (UAS) 731 This header is never sent to an untrusted UAS, and is never sent by 732 an untrusted UAS. 734 7.5. Procedures at a Trusted User Agent Server (UAS) 736 The UAS MUST include a P-DCS-Billing-Info header in the first 737 reliable 1xx (except 100) or 2xx response to an initial INVITE or 738 SUBSCRIBE message. This P-DCS-Billing-Info header MUST include the 739 Billing- Correlation-ID generated by the UAS, the FEID of the UAS, 740 and the RKS-Group-ID of the Record-Keeping-Server being used by the 741 UAS. The UAS MAY change the values of Acct-Charge-URI if it wishes 742 to override the billing information that was present in the INVITE 743 (e.g., for a toll-free call). The decision to do this and the 744 contents of the new Acct-Charge-URI MUST be determined by service 745 provider policy provisioned in the UAS. If the UAS performed a LNP 746 query, it MUST include the Routing Number and Location Routing Number 747 returned by the query. 749 The UAS MUST add a P-DCS-Billing-Info header to a 3xx-redirect 750 response to an initial INVITE, giving the accounting information for 751 the call forwarder, for the call segment from the destination to the 752 forwarded-to destination. 754 7.6. Procedures at Proxy 756 Three sets of proxy procedures are defined: (1) the procedures at an 757 originating proxy, (2) the procedures at a terminating proxy, and (3) 758 the procedures at a tandem proxy. 760 The originating proxy is a proxy that received the INVITE or 761 SUBSCRIBE request from a non-trusted endpoint. 763 The terminating proxy is a proxy that sends the INVITE or SUBSCRIBE 764 request to a non-trusted endpoint. 766 A proxy that is neither an originating proxy, nor a terminating 767 proxy, is a tandem proxy. 769 For purposes of mid-call changes, such as call transfers, the proxy 770 that receives the request from a non-trusted endpoint is considered 771 the initiating proxy; the proxy that sends the request to a non- 772 trusted endpoint is considered the recipient proxy. Procedures for 773 the initiating proxy are included below with those for originating 774 proxies, while procedures for the recipient proxy are included with 775 those for terminating proxies. 777 A proxy that both receives the request from an untrusted endpoint, 778 and sends the request to a non-trusted endpoint, performs both sets 779 of procedures. 781 7.6.1. Procedures at Originating Proxy 783 The originating proxy MUST generate the Billing-Correlation-ID for 784 the call, and insert it into the P-DCS-Billing-Info header in the 785 initial INVITE or SUBSCRIBE message sent to the terminating entity, 786 along with the charging information for the call. The originating 787 proxy MUST include its FEID, and the RKS-Group-ID for the Record- 788 Keeping-Server being used by the originating proxy. If the 789 originating proxy performed a LNP query, it MUST include the Routing 790 Number, Location Routing Number and JIP-param returned by the query. 791 Any P-DCS-Billing- Info header present from an untrusted UA MUST be 792 removed. 794 If the Request-URI contains a private-URL, and the decoded username 795 contains billing information, the originating proxy MUST generate a 796 P-DCS-Billing-Info header with that decrypted information. 797 Otherwise, the originating proxy MUST determine the accounting 798 information for the call originator, and insert a P-DCS-Billing-Info 799 header including that information. 801 If the response to the initial INVITE is a 3xx-Redirect, received 802 prior to a non-100 provisional response, the originating proxy 803 generates a new initial INVITE request to the destination specified 804 in the Contact: header, as per standard SIP. If an originating proxy 805 receives a 3xx-Redirect response to an initial INVITE prior to a non- 806 100 provisional response, the INVITE generated by the proxy MUST 807 contain the P-DCS-Billing-Info header from the 3xx-Redirect response. 809 If the response to the initial INVITE is a 3xx-Redirect, received 810 after a non-100 provisional response, the originating proxy generates 811 a private-URL and places it in the Contact header of a 3xx-Redirect 812 response sent to the originating endpoint. This private-URL MUST 813 contain (or contain a pointer to) the P-DCS-Billing-Info value, which 814 indicate the charging arrangement for the new call, and an expiration 815 time very shortly in the future, to limit the ability of the 816 originator to re-use this private-URL for multiple calls. 818 An originating proxy that processes a REFER request from an untrusted 819 UA MUST include a P-DCS-Billing-Info header in the Refer-to's URL. 820 This P-DCS-Billing-Info header MUST include the accounting 821 information of the initiator. 823 7.6.2. Procedures at Terminating Proxy 825 The terminating proxy MUST NOT send the P-DCS-Billing-Info header to 826 an untrusted destination. 828 The terminating proxy MUST include a P-DCS-Billing-Info header in the 829 first reliable 1xx (except 100) or 2xx response to an initial INVITE 830 or SUBSCRIBE message. This P-DCS-Billing-Info header MUST include 831 the Billing- Correlation-ID generated by the terminating proxy, the 832 FEID of the terminating proxy, and the RKS-Group-ID of the Record- 833 Keeping-Server being used by the terminating proxy. The terminating 834 proxy MAY change the values of Acct-Charge-URI if it wishes to 835 override the billing information that was present in the INVITE 836 (e.g., for a toll-free call). The decision to do this and the 837 contents of the resulting P-DCS-Billing-Info header MUST be 838 determined by service provider policy provisioned in the terminating 839 proxy. If the terminating proxy performed a LNP query, it MUST 840 include the Routing Number and Location Routing Number returned by 841 the query. 843 The terminating proxy MUST add P-DCS-Billing-Info headers to a 3xx- 844 redirect response to an initial INVITE, giving the accounting 845 information for the call forwarder, for the call segment from the 846 destination to the forwarded-to destination. 848 A proxy receiving a mid-call REFER request that includes a Refer-to 849 header generates a private-URL and places it in the Refer-to header 850 sent to the endpoint. This private-URL MUST contain the P-DCS- 851 Billing-Info value, which indicates the charging arrangement for the 852 new call, and an expiration time very shortly in the future, to limit 853 the ability of the endpoint to re-use this private-URL for multiple 854 calls. 856 7.6.3. Procedures at Tandem Proxy 858 If the tandem proxy performed a LNP query, it MUST insert the Routing 859 Number and Location Routing Number returned by the query into the P- 860 DCS-Billing-Info header in the first reliable 1xx/2xx/3xx (except 861 100) response. 863 8. P-DCS-LAES and P-DCS-REDIRECT 865 NOTE: According to RFC 2804 [RFC2804], the IETF supports 866 documentation of lawful intercept technology if it is necessary to 867 develop it. The following section provides such documentation. The 868 [RFC2119] language, as stated above, describes the requirements of 869 the specification only if implemented, and strictly within the 870 applicability domain described above. See RFC 2804 for description 871 of issues regarding privacy, security, and complexity in relation to 872 this technology. 874 The P-DCS-LAES extension contains the information needed to support 875 Lawfully Authorized Electronic Surveillance. This header contains 876 the address and port of an Electronic Surveillance Delivery Function 877 for delivery of a duplicate stream of event messages related to this 878 call and the associated BCID for the event stream. The header may 879 also contain an additional address and port for delivery of call 880 content and associated cccid. The P-DCS-LAES header is only used 881 between proxies and trusted User Agents. The P-DCS-LAES header 882 defined here is not backwards compatiable with that defined in 883 [RFC3603], which is deprecated by the document. This version of the 884 P-DCS-LAES header adds a ccc-id parameter to support the intercept of 885 content, and deletes security key information. 887 The P-DCS-Redirect extension contains call identifying information 888 needed to support the requirements of Lawfully Authorized Electronic 889 Surveillance of redirected calls. This header is only used between 890 proxies and trusted User Agents. 892 Use of P-DCS-LAES and P-DCS-Redirect is controlled by a combination 893 of legislation, regulation, and court orders, which MUST be followed. 894 In certain cases inclusion of these headers will be mandated, and 895 therefore MUST be present in the requests and responses indicated. 896 In other cases inclusion of these headers will be forbidden, and 897 therefore MUST NOT be present in the request and responses indicated. 898 In the sub-sections that follow, use of "SHOULD" is intended to 899 capture these conflicting situations, e.g., a P-DCS-LAES header 900 SHOULD be included in an initial INVITE means either that it MUST be 901 included or that it MUST NOT be included, based on the applicable 902 court orders. 904 8.1. Syntax 906 The formats of the P-DCS-LAES and P-DCS-Redirect headers are given by 907 the following ABNF (some terms used in this ABNF are defined in 908 [RFC3261] and [RFC4234]): 910 P-DCS-LAES = "P-DCS-LAES" HCOLON Laes-sig 911 *(SEMI Laes-param) 912 Laes-sig = hostport 913 Laes-param = Laes-content / Laes-cccid 914 Laes-bcid / generic-param 915 Laes-content = "content" EQUAL hostport 917 Laes-bcid = "bcid" EQUAL 1*48(HEXDIG) 918 Laes-cccid = "cccid" EQUAL 1*8(HEXDIG) 920 P-DCS-Redirect = "P-DCS-Redirect" HCOLON Called-ID 921 *(SEMI redir-params) 922 Called-ID = LDQUOT addr-spec RDQUOT 923 redir-params = redir-uri-param / redir-count-param / 924 generic-param 925 redir-uri-param = "redirector-uri" EQUAL Redirector 926 Redirector = LDQUOT addr-spec RDQUOT 927 redir-count-param = "count" EQUAL Redir-count 928 Redir-count = 1*DIGIT 930 This document adds the following entry to Table 2 of [RFC3261]: 931 Header field where proxy ACK BYE CAN INV OPT REG PUB 932 ------------ ----- ----- --- --- --- --- --- --- --- 933 P-DCS-LAES adr - - - o - - - 934 P-DCS-Redirect adr - - - o - - - 936 SUB NOT REF INF UPD PRA MSG 937 --- --- --- --- --- --- --- 938 - - - - - - - 939 - - - - - - - 941 The values of Laes-sig and Laes-content are addresses of the 942 Electronic Surveillance Delivery Function, and used as the 943 destination address for call-identifying information and call- 944 content, respectively. [PCSEC]. Laes-bcid contains a correlation ID 945 that is used to link a sequence of intercepted call processing events 946 related to a single call. Laes-cccid contains an identifier of the 947 intercepted call content. The Laes-bcid field MUST always be 948 present. The Laes-cccid field MUST be present when the Laes-content 949 field is present. 951 The P-DCS-Redirect header contains redirection information. The 952 Called-ID indicates the original destination requested by the user 953 (e.g., number dialed orginally), the redir-uri-param indicates the 954 entity performing the redirectoin, and the Redir-count indicates the 955 number of redirections that have occurred. For example, if A calls 956 B, who forwards to C, who forwards to D, then, when C forwards to D, 957 the Called-ID will be A, redir-uri-param will be C, and count will be 958 2. 960 8.2. Procedures at an Untrusted User Agent Client (UAC) 962 This header MUST NOT be sent to an untrusted UAC, and MUST NOT be 963 sent by an untrusted UAC. 965 8.3. Procedures at a Trusted User Agent Client (UAC) 967 The UAC checks for an outstanding lawfully authorized surveillance 968 order for the originating subscriber, and, if present, includes this 969 information in the Authorization for Quality of Service [PCDQOS] or 970 signals this information to the device performing the intercept 971 (e.g., a Media Gateway). 973 If the P-DCS-LAES header is present in the first reliable 1xx (except 974 100), 2xx or 3xx response (indicating surveillance is required on the 975 terminating subscriber, but that the terminating equipment is unable 976 to perform that function), the UAC MUST include this information in 977 the Authorization for Quality of Service, or MUST signal this 978 information to the device performing the intercept (e.g., a Media 979 Gateway). 981 If a 3xx-Redirect response is received to the initial INVITE request, 982 and if a P-DCS-LAES header is present in the 3xx response, the UAC 983 SHOULD include that header unchanged in the reissued INVITE. The UAC 984 SHOULD also include a P-DCS-Redirect header containing the original 985 dialed number, the most recent redirecting party, and the number of 986 redirections that have occurred. Although it is technically possible 987 for the originating equipment to perform this surveillance (or add to 988 its existing surveillance of the call), the design of the 989 surveillance system has the terminating equipment performing the 990 surveillance for all the intermediate forwardings. 992 A UAC that includes a Refer-to header in a REFER request, when the 993 originating subscriber has an outstanding lawfully authorized 994 surveillance order, SHOULD include a P-DCS-LAES header attached to 995 the Refer-to. The UAC may also include a P-DCS-Redirect header. The 996 P-DCS-LAES header SHOULD include the Laes-bcid parameter set to a 997 value that uniquely identifies the call, SHOULD include the address 998 and port of the local Electronic Surveillance Delivery Function for a 999 copy of the call's event messages, SHOULD include the address and 1000 port of the local Electronic Surveillance Delivery Function for the 1001 copy of call content if call content is to be intercepted, and SHOULD 1002 include the Laes-cccid parameter set to a value that uniquely 1003 identifies the intercepted audio stream if call content is to be 1004 intercepted. 1006 The trusted UAC MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1007 headers to an untrusted entity. 1009 8.4. Procedures at an Untrusted User Agent Server (UAS) 1011 This header MUST NOT be sent to an untrusted UAS, and MUST NOT be 1012 sent by an untrusted UAS. 1014 8.5. Procedures at a Trusted User Agent Server (UAS) 1016 The UAS checks for an outstanding lawfully authorized surveillance 1017 order for the terminating subscriber, or presence of the P-DCS-LAES 1018 header in the INVITE request. If either is present, the UAS includes 1019 this information in the authorization for Quality of Service 1020 [PCDQOS]. 1022 If the terminating equipment is unable to perform the required 1023 surveillance (e.g., if the destination is a voicemail server), the 1024 UAS SHOULD include a P-DCS-LAES header in the first reliable 1xx 1025 (except 100), 2XX or 3XX response requesting the originating proxy to 1026 perform the surveillance. The P-DCS-LAES header SHOULD include the 1027 Laes-bcid parameter with a value that uniquely identifies the call, 1028 SHOULD include the address and port of the local Electronic 1029 Surveillance Delivery Function for a copy of the call's event 1030 messages, SHOULD include the address and port of the local Electronic 1031 Surveillance Delivery Function for the copy of call content if call 1032 content is to be intercepted, and SHOULD include the Laes-cccid 1033 parameter set to a value that uniquely identifies the intercepted 1034 audio stream if call content is to be intercepted. 1036 If the response to the initial INVITE request is a 3xx-Redirect 1037 response, and there is an outstanding lawfully authorized 1038 surveillance order for the terminating subscriber, the UAS SHOULD 1039 include a P-DCS-LAES header in the 3xx-Redirect response, with 1040 contents as described above. 1042 The trusted UAS MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1043 headers to an untrusted entity. 1045 8.6. Procedures at Proxy 1047 Two sets of proxy procedures are defined: (1) the procedures at an 1048 originating proxy, and (2) the procedures at a terminating proxy. 1049 The originating proxy is a proxy that received the INVITE request 1050 from a non-trusted endpoint. 1052 The terminating proxy is a proxy that sends the INVITE request to a 1053 non-trusted endpoint. 1055 For purposes of mid-call changes, such as call transfers, the proxy 1056 that receives the request from a non-trusted endpoint is considered 1057 the initiating proxy; the proxy that sends the request to a non- 1058 trusted endpoint is considered the recipient proxy. Procedures for 1059 the initiating proxy are included below with those for originating 1060 proxies, while procedures for the recipient proxy are included with 1061 those for terminating proxies. 1063 A proxy that both receives the INVITE request from an untrusted 1064 endpoint, and sends the INVITE request to a non-trusted endpoint, 1065 MUST NOT generate P-DCS-LAES nor P-DCS-Redirect headers. 1067 A proxy that is neither an originating proxy nor a terminating proxy 1068 SHOULD pass the P-DCS-Laes and P-DCS-Redirect headers in requests and 1069 responses. 1071 8.6.1. Procedures at Originating Proxy 1073 The Originating Proxy MUST remove any P-DCS-LAES and P-DCS-Redirect 1074 headers in requests or responses to or from an untrusted proxy or 1075 untrusted UA. 1077 The originating proxy checks for an outstanding lawfully authorized 1078 surveillance order for the originating subscriber, and, if present, 1079 includes this information in the Authorization for Quality of Service 1080 [PCDQOS] or signals this information to the device performing the 1081 intercept (e.g., a Media Gateway). 1083 If the P-DCS-LAES header is present in the first reliable 1xx (except 1084 100), 2xx or 3xx response (indicating surveillance is required on the 1085 terminating subscriber, but that the terminating equipment is unable 1086 to perform that function), the originating proxy MUST include this 1087 information in the Authorization for Quality of Service, or MUST 1088 signal this information to the device performing the intercept (e.g., 1089 a Media Gateway). 1091 If the Request-URI in an initial INVITE request contains a private- 1092 URL, the originating proxy MUST decrypt the userinfo information to 1093 find the real destination for the call, and other special processing 1094 information. If electronic surveillance information is contained in 1095 the decrypted userinfo, the originating proxy SHOULD generate a P- 1096 DCS-LAES and (if neccessary) a P-DCS-REDIRECT header with the 1097 surveillance information. 1099 If a 3xx-Redirect response is received to the initial INVITE request 1100 prior to a non-100 provisional response, and if a P-DCS-LAES header 1101 is present in the 3xx response, the originating proxy SHOULD include 1102 that header unchanged in the reissued INVITE. The originating proxy 1103 SHOULD also include a P-DCS-Redirect header containing the original 1104 dialed number, the most recent redirecting party, and the number of 1105 redirections that have occurred. 1107 If a 3xx-Redirect response is received to the initial INVITE request 1108 after a non-100 provisional response, the originating proxy generates 1109 a private-URL and places it in the Contact header of a 3xx-Redirect 1110 response sent to the originating endpoint. If a P-DCS-LAES header is 1111 present in the 3xx response, this private-URL MUST contain (1) the 1112 electronic surveillance information from the 3xx-Redirect response, 1113 (2) the original destination number, (3) the identity of the 1114 redirecting party, and (4) the number of redirections of this call. 1116 An originating proxy that processes a REFER request [RFC3515] from an 1117 untrusted UA, when the originating subscriber has an outstanding 1118 lawfully authorized surveillance order, becomes a B2BUA for that 1119 request. It SHOULD reissue the request with a P-DCS-LAES header 1120 added to the Refer-to's URL. It MAY also include a P-DCS-REDIRECT 1121 header. The P-DCS-LAES header SHOULD include (1) the Laes-bcid 1122 parameter set to a value that uniquely identifies the call, (2) the 1123 address and port of the local Electronic Surveillance Delivery 1124 Function for a copy of the call's event messages, (3) the address and 1125 port of the local Electronic Surveillance Delivery Function for the 1126 copy of call content if call content is to be intercepted, and (4) 1127 SHOULD include the Laes-cccid parameter set to a value that uniquely 1128 identifies the intercepted audio stream if call content is to be 1129 intercepted. 1131 An initiating proxy that sends a mid-call REFER request including a 1132 Refer-to header, when the initiating subscriber has an outstanding 1133 lawfully authorized surveillance order, SHOULD include a P-DCS-LAES 1134 header in the Refer-to's URL. 1136 The originating proxy MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1137 headers to an untrusted entity. 1139 8.6.2. Procedures at Terminating Proxy 1141 The Terminating Proxy MUST remove any P-DCS-LAES and P-DCS-Redirect 1142 headers in requests or responses to or from an untrusted proxy or UA. 1144 The terminating proxy checks for an outstanding lawfully authorized 1145 surveillance order for the terminating subscriber. If present, the 1146 terminating proxy includes this information in the authorization for 1147 Quality of Service [PCDQOS]. 1149 The terminating proxy MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1150 headers to an untrusted entity, either as headers in the request or 1151 response, or as headers attached to URIs in the request or response. 1153 If the terminating equipment is unable to perform the required 1154 surveillance (e.g., if the destination is a voicemail server), the 1155 terminating proxy SHOULD include a P-DCS-LAES header in the first 1156 reliable 1xx/2xx/3xx (except 100) response requesting the originating 1157 proxy to perform the surveillance. The P-DCS-LAES header SHOULD 1158 include the Laes-bcid parameter set to a value that uniquely 1159 identifies the call, SHOULD include the address and port of the local 1160 Electronic Surveillance Delivery Function for a copy of the call's 1161 event messages, SHOULD include the address and port of the local 1162 Electronic Surveillance Delivery Function for the copy of call 1163 content if call content is to be intercepted, and SHOULD include the 1164 Laes-cccid parameter set to a value that uniquely identifies the 1165 audio stream if call content is to be intercepted. 1167 If the response to the initial INVITE request is a 3xx-Redirect 1168 response, and there is an outstanding lawfully authorized 1169 surveillance order for the terminating subscriber, the terminating 1170 proxy SHOULD include a P-DCS-LAES header in the 3xx-Redirect 1171 response, with contents as described above. 1173 A proxy receiving a mid-call REFER request [RFC3515] that includes a 1174 Refer-to header with a P-DCS-LAES header attached becomes a B2BUA for 1175 this request. It MUST generate a private-URL and place it in the 1176 Refer-to header sent to the endpoint. This private-URL MUST contain 1177 the P-DCS-LAES and P-DCS-REDIRECT information from the attached 1178 header. 1180 9. Security Considerations 1182 QoS gate coordination, billing information, and electronic 1183 surveillance information are all considered to be sensitive 1184 information that MUST be protected from eavesdropping and furthermore 1185 require integrity checking. It is therefore necessary that the 1186 trusted UAs and proxies take precautions to protect this information 1187 from eavesdropping and tampering. Use of IPsec or TLS between 1188 Proxies and Trusted User Agents is REQUIRED. A minimum mandatory-to- 1189 implement IPsec configuration for the DCS architecture is given by 1190 [PCSEC]. Also REQUIRED is mutual authentication (1) between Proxies 1191 and (2) between trusted UAs and Proxies, both of which MAY be 1192 implemented with administratively pre-shared keys, or through 1193 consultation with another trusted third party. If IPsec is to be 1194 used, the specification of the security policies and procedures of 1195 the administrative domain where these headers are applicable (and all 1196 connections between administrative domains in the federation) MUST 1197 define an interoperable set of options. 1199 10. IANA Considerations 1201 This document updates a number of SIP extension headers, which have 1202 previously been included in the registry of SIP headers defined in 1203 [RFC3261]. Registration information for the updated headers is as 1204 follows: 1206 Header Field Name: P-DCS-Trace-Party-ID 1207 RFC Number: [RFC Editor: Please add assigned RFC number] 1208 Compact Form: none 1209 Header Field Name: P-DCS-OSPS 1210 RFC Number: [RFC Editor: Please add assigned RFC number] 1211 Compact Form: none 1212 Header Field Name: P-DCS-Billing-Info 1213 RFC Number: [RFC Editor: Please add assigned RFC number] 1214 Compact Form: none 1215 Header Field Name: P-DCS-LAES 1216 RFC Number: [RFC Editor: Please add assigned RFC number] 1217 Compact Form: none 1218 Header Field Name: P-DCS-Redirect 1219 RFC Number: [RFC Editor: Please add assigned RFC number] 1220 Compact Form: none 1222 11. Change Log 1224 o A timestamp parameter is added to the P-DCS-Trace-Party-ID header 1225 when available. Procedures on the use of the Target-Dialog header 1226 used together with the P-DCS-Trace-Party-ID are added. 1228 o The JIP parameter is added to the P-DCS-Billing-Infor header when 1229 available 1231 o The BCID billing correlation identifier and cccid call content 1232 channel identifier are addded to the P-DCS-LAES header. 1234 o P-DCS-Billing-Info header is applied to the SUBSCRIBE method. 1236 o P-DCS-REDIRECT header is applied to the REFER method. 1238 o PUBLISH and MESSAGE methods are addded to the SIP method 1239 applicability matrices throughout. 1241 12. Acknowledgements 1243 The Distributed Call Signaling work in the PacketCable project is the 1244 work of a large number of people, representing many different 1245 companies. The authors would like to recognize and thank the 1246 following for their assistance: John Wheeler, Motorola; David 1247 Boardman, Daniel Paul, Arris Interactive; Bill Blum, Jon Fellows, Jay 1248 Strater, Jeff Ollis, Clive Holborow, Motorola; Doug Newlin, Guido 1249 Schuster, Ikhlaq Sidhu, 3Com; Jiri Matousek, Bay Networks; Farzi 1250 Khazai, Nortel; John Chapman, Bill Guckel, Michael Ramalho, Cisco; 1251 Chuck Kalmanek, Doug Nortz, John Lawser, James Cheng, Tung- Hai 1252 Hsiao, Partho Mishra, AT&T; Telcordia Technologies; and Lucent Cable 1253 Communications. 1255 Previous versions further acknowledged, as co-authors, several people 1256 for providing the text of this document. They are: 1258 Bill Marshall (wtm@research.att.com) and K. K. Ramakrishnan 1259 (kkrama@research.att.com), AT&T; Ed Miller 1260 (edward.miller@terayon.com), Terayon; David Hancock (D.Hancock@ 1261 Cablelabs.com) and Glenn Russell (G.Russell@Cablelabs.com), 1262 CableLabs; Burcak Beser (burcak@juniper.net) Juniper Networks, Mike 1263 Mannette (Michael_Mannette@3com.com) and Kurt Steinbrenner 1264 (Kurt_Steinbrenner@3com.com), 3Com; Dave Oran (oran@cisco.com) and 1265 Flemming Andreasen (fandreas@cisco.com), Cisco Systems; John Pickens 1266 (jpickens@com21.com), Com21; Poornima Lalwaney 1267 (poornima.lalwaney@nokia.com), Nokia; Jon Fellows 1268 (jfellows@coppermountain.com), Copper Mountain Networks; Doc Evans 1269 (n7dr@arrisi.com) Arris, and Keith Kelly (keith@netspeak.com), 1270 NetSpeak. 1272 13. References 1274 13.1. Normative References 1276 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1277 Requirement Levels", BCP 14, RFC 2119, March 1997. 1279 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 1280 A., Peterson, J., Sparks, R., Handley, M., and E. 1281 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 1282 June 2002. 1284 [RFC3515] Sparks, R., "The Session Initiation Protocol (SIP) Refer 1285 Method", RFC 3515, April 2003. 1287 [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 1288 Specifications: ABNF", RFC 4234, October 2005. 1290 [RFC4330] Mills, D., "Simple Network Time Protocol (SNTP) Version 4 1291 for IPv4, IPv6 and OSI", RFC 4330, January 2006. 1293 [RFC4538] Rosenberg, J., "Request Authorization through Dialog 1294 Identification in the Session Initiation Protocol (SIP)", 1295 RFC 4538, June 2006. 1297 13.2. Informative References 1299 [DCSARCH] Marshall, W., Osman, M., Andreasen, F., and D. Evans, 1300 "Architectural Considerations for Providing Carrier Class 1301 Telephony Services Utilizing SIP-based Distributed Call 1302 Control Mechanisms", Jan 2003. 1304 [PCDQOS] Cable Television Laboratories, Inc., "PacketCable 1.5 1305 Specifications, Dynamic Quality of Service", Aug 2005. 1307 [PCEM] Cable Television Laboratories, Inc., "PacketCable 1.5 1308 Specifications, Event Messages", Dec 2005. 1310 [PCSEC] Cable Television Laboratories, Inc., "PacketCable 1.5 1311 Specifications, Security", Jan 2005. 1313 [RFC2804] IAB and IESG, "IETF Policy on Wiretapping", RFC 2804, 1314 May 2000. 1316 [RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private 1317 Extensions to the Session Initiation Protocol (SIP) for 1318 Asserted Identity within Trusted Networks", RFC 3325, 1319 November 2002. 1321 [RFC3603] Marshall, W. and F. Andreasen, "Private Session Initiation 1322 Protocol (SIP) Proxy-to-Proxy Extensions for Supporting 1323 the PacketCable Distributed Call Signaling Architecture", 1324 RFC 3603, October 2003. 1326 Authors' Addresses 1328 Flemming Andreasen 1329 Cisco 1330 Edison, NJ 1331 USA 1333 Email: fandreas@cisco.com 1335 Bernie McKibben 1336 CableLabs 1337 Louisville, CO 1338 USA 1340 Email: B.McKibben@cablelabs.com 1342 Bill Marshall 1343 AT&T 1344 Florham Park, NJ 1345 USA 1347 Email: wtm@research.att.com 1349 Full Copyright Statement 1351 Copyright (C) The IETF Trust (2007). 1353 This document is subject to the rights, licenses and restrictions 1354 contained in BCP 78, and except as set forth therein, the authors 1355 retain all their rights. 1357 This document and the information contained herein are provided on an 1358 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 1359 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 1360 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 1361 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 1362 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 1363 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1365 Intellectual Property 1367 The IETF takes no position regarding the validity or scope of any 1368 Intellectual Property Rights or other rights that might be claimed to 1369 pertain to the implementation or use of the technology described in 1370 this document or the extent to which any license under such rights 1371 might or might not be available; nor does it represent that it has 1372 made any independent effort to identify any such rights. Information 1373 on the procedures with respect to rights in RFC documents can be 1374 found in BCP 78 and BCP 79. 1376 Copies of IPR disclosures made to the IETF Secretariat and any 1377 assurances of licenses to be made available, or the result of an 1378 attempt made to obtain a general license or permission for the use of 1379 such proprietary rights by implementers or users of this 1380 specification can be obtained from the IETF on-line IPR repository at 1381 http://www.ietf.org/ipr. 1383 The IETF invites any interested party to bring to its attention any 1384 copyrights, patents or patent applications, or other proprietary 1385 rights that may cover technology that may be required to implement 1386 this standard. Please address the information to the IETF at 1387 ietf-ipr@ietf.org. 1389 Acknowledgment 1391 Funding for the RFC Editor function is provided by the IETF 1392 Administrative Support Activity (IASA).