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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 30, 2009 B. Marshall 7 AT&T 8 November 26, 2008 10 Private Session Initiation Protocol (SIP) Proxy-to-Proxy Extensions for 11 Supporting the PacketCable Distributed Call Signaling Architecture 12 draft-andreasen-sipping-rfc3603bis-07 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 30, 2009. 39 Abstract 41 In order to deploy a residential telephone service at very large 42 scale across different domains, it is necessary for trusted elements 43 owned by different service providers to exchange trusted information 44 that conveys customer-specific information and expectations about the 45 parties involved in the call. This document describes private 46 extensions to the Session Initiation Protocol (SIP) [RFC3261] for 47 supporting the exchange of customer information and billing 48 information between trusted entities in the PacketCable Distributed 49 Call Signaling Architecture. These extensions provide mechanisms for 50 access network coordination to prevent theft of service, customer 51 originated trace of harassing calls, support for operator services 52 and emergency services, and support for various other regulatory 53 issues. The use of the extensions is only applicable within closed 54 administrative domains, or among federations of administrative 55 domains with previously agreed-upon policies where coordination of 56 charging and other functions is required. 58 Table of Contents 60 1. Applicability Statement . . . . . . . . . . . . . . . . . . . 5 61 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6 62 3. Trust Boundary . . . . . . . . . . . . . . . . . . . . . . . . 8 63 4. Conventions used in this document . . . . . . . . . . . . . . 9 64 5. P-DCS-TRACE-PARTY-ID . . . . . . . . . . . . . . . . . . . . . 10 65 5.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 10 66 5.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 11 67 5.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 12 68 5.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 12 69 5.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 12 70 5.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 12 71 5.6.1. Procedures at Originating Proxy . . . . . . . . . . . 12 72 5.6.2. Procedures at Terminating Proxy . . . . . . . . . . . 13 73 6. P-DCS-OSPS . . . . . . . . . . . . . . . . . . . . . . . . . . 14 74 6.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 14 75 6.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 15 76 6.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 15 77 6.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 15 78 6.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 16 79 6.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 16 80 7. P-DCS-BILLING-INFO . . . . . . . . . . . . . . . . . . . . . . 17 81 7.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 18 82 7.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 20 83 7.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 21 84 7.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 21 85 7.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 21 86 7.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 22 87 7.6.1. Procedures at Originating Proxy . . . . . . . . . . . 22 88 7.6.2. Procedures at Terminating Proxy . . . . . . . . . . . 23 89 7.6.3. Procedures at Tandem Proxy . . . . . . . . . . . . . . 24 90 8. P-DCS-LAES and P-DCS-Redirect . . . . . . . . . . . . . . . . 25 91 8.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 26 92 8.2. Procedures at an Untrusted User Agent Client (UAC) . . . . 27 93 8.3. Procedures at a Trusted User Agent Client (UAC) . . . . . 27 94 8.4. Procedures at an Untrusted User Agent Server (UAS) . . . . 28 95 8.5. Procedures at a Trusted User Agent Server (UAS) . . . . . 28 96 8.6. Procedures at Proxy . . . . . . . . . . . . . . . . . . . 29 97 8.6.1. Procedures at Originating Proxy . . . . . . . . . . . 29 98 8.6.2. Procedures at Terminating Proxy . . . . . . . . . . . 31 99 9. Security Considerations . . . . . . . . . . . . . . . . . . . 33 100 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 101 11. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 36 102 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 37 103 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38 104 13.1. Normative References . . . . . . . . . . . . . . . . . . . 38 105 13.2. Informative References . . . . . . . . . . . . . . . . . . 38 107 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 40 108 Intellectual Property and Copyright Statements . . . . . . . . . . 41 110 1. Applicability Statement 112 The SIP extensions described in this document make certain 113 assumptions regarding network topology, linkage between SIP and lower 114 layers, and the availability of transitive trust. These assumptions 115 are generally not applicable in the Internet as a whole. The use of 116 these headers is only applicable within closed administrative 117 domains, or among federations of administrative domains with 118 previously agreed-upon policies where coordination of charging and 119 other functions is required, as in for example the architecture 120 presented in [DCSARCH]. Use outside such a domain could result in 121 the leakage of potentially sensitive or private information. User 122 consent to the privacy implications of the policies in [DCSARCH] is 123 strongly encouraged in those domains as well. 125 Although [RFC2119] language is used in this document, the scope of 126 the normative language is only for the area of applicability of the 127 document and, like the technology, it does not apply to the general 128 Internet. 130 2. Introduction 132 In order to deploy a SIP-based [RFC3261] residential telephone 133 service at very large scale across different domains, it is necessary 134 for trusted elements owned by different service providers to exchange 135 trusted information that conveys billing information and expectations 136 about the parties involved in the call. 138 There are many billing models used in deriving revenue from telephony 139 services today. Charging for telephony services is tightly coupled 140 to the use of network resources. It is outside the scope of this 141 document to discuss the details of these numerous and varying 142 methods. 144 A key motivating principle of the DCS architecture described in 145 [DCSARCH] is the need for network service providers to be able to 146 control and monitor network resources; revenue may be derived from 147 the usage of these resources as well as from the delivery of enhanced 148 services such as telephony. Furthermore, the DCS architecture 149 recognizes the need for coordination between call signaling and 150 resource management. This coordination ensures that users are 151 authenticated and authorized before receiving access to network 152 resources and billable enhanced services. 154 DCS Proxies, as defined in [DCSARCH], have access to subscriber 155 information and act as policy decision points and trusted 156 intermediaries along the call signaling path. Edge routers provide 157 the network connectivity and resource policy enforcement mechanism 158 and also capture and report network connectivity and resource usage 159 information. Edge routers need to be given billing information that 160 can be logged with Record Keeping or Billing servers. The DCS Proxy, 161 as a central point of coordination between call signaling and 162 resource management, can provide this information based on the 163 authenticated identity of the calling and called parties. Since 164 there is a trust relationship among DCS Proxies, they can be relied 165 upon to exchange trusted billing information pertaining to the 166 parties involved in a call. See [DCSARCH] for a description of the 167 trust boundary and trusted versus untrusted entities. 169 For these reasons, it is appropriate to consider defining SIP header 170 extensions to allow DCS Proxies to exchange information during call 171 setup. It is the intent that the extensions would only appear on 172 trusted network segments, should be inserted upon entering a trusted 173 network region, and removed before leaving trusted network segments. 175 Significant amounts of information are retrieved by an originating 176 DCS Proxy in its handling of a connection setup request from a user 177 agent. Such information includes location information about the 178 subscriber (essential for emergency services calls), billing 179 information, and station information (e.g., coin operated phone). In 180 addition, while translating the destination number, information such 181 as the local-number-portability office code is obtained and will be 182 needed by all other proxies handling this call. 184 For Usage Accounting records, it is necessary to have an identifier 185 that can be associated with all the event records produced for the 186 call. The SIP Call-ID header field cannot be used as such an 187 identifier since it is selected by the originating user agent, and 188 may not be unique among all past calls as well as current calls. 189 Further, since this identifier is to be used by the service provider, 190 it should be chosen in a manner and in a format that meets the 191 service provider's needs. 193 Billing information may not necessarily be unique for each user 194 (consider the case of calls from an office all billed to the same 195 account). Billing information may not necessarily be identical for 196 all calls made by a single user (consider prepaid calls, credit card 197 calls, collect calls, etc). It is therefore necessary to carry 198 billing information separate from the calling and called party 199 identification. Furthermore, some billing models call for split- 200 charging where multiple entities are billed for portions of the call. 202 The addition of a SIP General Header Field allows for the capture of 203 billing information and billing identification for the duration of 204 the call. 206 It is the intent that the billing extensions would only appear on 207 trusted network segments, and MAY be inserted by a DCS Proxy in 208 INVITE and REFER requests and INVITE responses in a trusted network 209 segment, and removed before leaving trusted network segments. 211 In addition to support for billing, current residential telephone 212 service includes the need for customer originated trace (of harassing 213 or obscene calls), for operator services such as busy line 214 verification and emergency interrupt (initiated by an operator from 215 an Operator Services Position System (OSPS)), for emergency services 216 such as 9-1-1 calls to a Public Service Access Point (PSAP) and the 217 subsequent call handling, and support for Electronic Surveillance and 218 Law Enforcement access as required by applicable legislation and 219 court orders. In all of these cases, additional information about 220 the call and about the subscribers involved in the call needs to be 221 exchanged between the proxies. 223 3. Trust Boundary 225 The DCS architecture [DCSARCH] defines a trust boundary around the 226 various systems and servers that are owned, operated by, and/or 227 controlled by the service provider. These trusted systems include 228 the proxies and various servers such as bridge servers, voicemail 229 servers, announcement servers, etc. Outside of the trust boundary 230 lie the customer premises equipment, and various application and 231 media servers operated by third-party service providers. 233 Certain subscriber-specific information, such as billing and 234 accounting information, stays within the trust boundary. Other 235 subscriber-specific information, such as endpoint identity, may be 236 presented to untrusted endpoints or may be withheld based on 237 subscriber profiles. 239 The User Agent (UA) may be either within the trust boundary or 240 outside the trust boundary, depending on exactly what function is 241 being performed and exactly how it is being performed. Accordingly, 242 the procedures followed by a User Agent are different depending on 243 whether the UA is within the trust boundary or outside the trust 244 boundary. 246 The following sections giving procedures for User Agents therefore 247 are subdivided into trusted user agents and untrusted user agents. 249 4. Conventions used in this document 251 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 252 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 253 document are to be interpreted as described in BCP 14, [RFC2119]. 255 The term "private-URL" used in this document refers to a SIP URI that 256 is generated by a proxy, contains a "hostport" that identifies the 257 proxy, and contains a "userinfo" string that is generated by the 258 proxy. The "userinfo" typically contains (or points to) information 259 that is not to be disclosed outside the trusted domain of the 260 proxies, such as billing account numbers, electronic surveillance 261 indication, electronic surveillance parameters, and call redirection 262 information. Consequently, the information is either stored locally 263 by the proxy, or encrypted with a private key known only to the proxy 264 and encoded in a character string in the "userinfo" portion of the 265 URL. A checksum is included in the "userinfo" data to detect 266 tampering. The mechanism by which a proxy recognizes a "userinfo" as 267 a private-URL and decodes and recovers the original information is 268 local to the proxy and is not subject to standardization. Some 269 possible implementations include an initial magic cookie (e.g., 270 z9hG4Bk followed by the pointer/information), or use of a reserved 271 "user" name (e.g., "private") with the optional "password" containing 272 the pointer/information. 274 5. P-DCS-TRACE-PARTY-ID 276 In the telephone network, calling identity information is used to 277 support regulatory requirements such as the Customer Originated Trace 278 service, which provide the called party with the ability to report 279 obscene or harassing phone calls to law enforcement. This service is 280 provided independently of caller-id, and works even if the caller 281 requested anonymity. The calling party is here identified as the 282 station originating the call. In order for this service to be 283 dependable, the called party must be able to trust that the calling 284 identity information being presented is valid. One way to achieve 285 this is described in [RFC3325]. 287 To initiate a customer-originated-trace from an untrusted UAC, an 288 additional header is defined for the INVITE request. This header is 289 called P-DCS-Trace-Party-ID, and does not appear in any other request 290 or response. The untrusted UAC also includes the Target-Dialog 291 header field defined in [RFC4538] in the INVITE request in order to 292 explicitly identify the call to be traced. The entity addressed by 293 the Request-URI performs the service-provider-specific functions of 294 recording and reporting the caller identity in the 295 P-DCS-Trace-Party-ID for law enforcement action. It then forwards 296 the call to either an announcement server or to the service- 297 provider's business office to collect further information about the 298 complaint. A trusted UAC does not use this header, as it initiates 299 this action locally. 301 5.1. Syntax 303 The ABNF description of this header is (some terms used in this ABNF 304 are defined in [RFC3261]): 306 P-DCS-Trace-Party-ID = "P-DCS-Trace-Party-ID" HCOLON name-addr *1(SEMI 307 timestamp-param) *(SEMI trace-param) 308 timestamp-param = "timestamp=" 1*DIGIT ["." 1*DIGIT] 309 trace-param = generic-param ;generic-param defined in RFC3261 310 This document adds the following entry to Table 2 of [RFC3261]: 312 Header field where proxy ACK BYE CAN INV OPT REG PUB 313 ------------ ----- ----- --- --- --- --- --- --- --- 314 P-DCS-Trace-Party-ID R dmr - - - o - - - 315 SUB NOT REF INF UPD PRA MSG 316 --- --- --- --- --- --- --- 317 - - - - - - - 319 The addr-spec contained in name-addr contains a URL that identifies 320 the remote endpoint. Addr-spec typically contains a tel URL or SIP 321 URI giving the identity of the remote endpoint, as provided in the 322 signaling messages that established the session to be traced. 324 The timestamp-param contains the value of the time the UA determines 325 it received the session initiation request of the call requested to 326 be traced. The timestamp-param is populated using the Network Time 327 Protocol timestamp format defined in RFC 1305 [RFC1305] and used by 328 the Simple Network Time Protocol [RFC4330]. The timestamp SHOULD be 329 encoded in UTF-8 Format per [RFC3629].The trace-param is a generic 330 parameter for future extensions. 332 An example of the P-DCS-Trace-Party-ID header is shown as follows: 334 P-DCS-Trace-Party-ID: sip:+12345678912@domain.com; user=phone; 335 timestamp=3434688831.2327 337 5.2. Procedures at an Untrusted User Agent Client (UAC) 339 The UAC MUST insert a P-DCS-Trace-Party-ID header into the initial 340 INVITE message for a customer-originated-trace request. The trace 341 request from the Untrusted User Agent Client is able to be initiated 342 during the dialog or after the release of the dialog or call that is 343 requested to be traced. The UAC MUST use a SIP URI in the Request- 344 URI with userinfo set to "call-trace" and hostport identifying the 345 call tracing entity for the untrusted UA. The [RFC3603] version of 346 the P-DCS-Trace-Party-ID did not include the timestamp-param 347 parameter, however the syntax is backwards compatible with [RFC3603]. 348 A UAC compliant to this updated specification MUST insert the 349 timestamp and the Target-Dialog header field defined in [RFC4538] if 350 known to the UAC. 352 In case of an anonymous malicious call, where the remote party is not 353 known to the Untrusted UAC, the Untrusted UAC SHOULD indicate the 354 user as anonymous in the P-DCS-Trace-Party-ID, for example, as 355 follows: sip:anonymous@anonymous.invalid. 357 5.3. Procedures at a Trusted User Agent Client (UAC) 359 A trusted UAC performs the customer-originated-trace in a manner 360 similar to the trusted UAS, described below. A trusted UAC MUST NOT 361 include this header in any request. 363 5.4. Procedures at an Untrusted User Agent Server (UAS) 365 This header MUST NOT appear in any response sent by a UAS. 367 5.5. Procedures at a Trusted User Agent Server (UAS) 369 If the P-DCS-Trace-Party-ID header is present in the initial INVITE 370 request from a UAC, and the Request-URI of the INVITE has userinfo 371 set to "call-trace" and hostport set to the UAS, the UAS MUST perform 372 the service-provider-specific functions of recording and reporting 373 the caller identity and associated trace parameters (if any) from the 374 Target-Dialog header field for law enforcement action. The UAS then 375 MUST redirect the call, via a 3xx response, to either an announcement 376 server or to the service-provider's business office to collect 377 further information about the complaint. 379 This header MUST NOT appear in any response sent by a UAS. 381 If the P-DCS-Trace-Party-ID header is not present in the initial 382 INVITE request from a UAC, and the Request-URI of the INVITE has 383 userinfo set to "call-trace" the UAS MUST reject the request. 385 5.6. Procedures at Proxy 387 Two sets of proxy procedures are defined: (1) the procedures at an 388 originating proxy, and (2) the procedures at a terminating proxy. 389 The originating proxy is a proxy that received the INVITE request 390 from a non-trusted endpoint. 392 The terminating proxy is a proxy that sends the INVITE request to a 393 non-trusted endpoint. 395 A proxy that both receives the INVITE request from an untrusted 396 endpoint, and sends the INVITE request to an untrusted endpoint, 397 performs both sets of procedures. 399 5.6.1. Procedures at Originating Proxy 401 If the P-DCS-Trace-Party-ID header is present in the initial INVITE 402 request from the UAC, and the Request-URI of the INVITE has userinfo 403 other than "call-trace" and hostport set to other than a potentially 404 provisioned call tracing entity, then the Proxy MAY reject the 405 request, or MAY remove the P-DCS-Trace-Party-ID header from the 406 request. If the header is present in a valid request, and contains a 407 private-URL that identifies the Proxy in the hostport, then the 408 Originating Proxy SHOULD replace the private-URL with its original 409 contents (i.e., the verified identity of the caller of the session 410 that is being traced and trace parameters from the Target-Dialog 411 header fields defined in [RFC4538]). 413 The proxy records the caller URL and target dialog IDs on sessions 414 directed toward the untrusted UAC if provisioned to do so by the 415 network operator. If the is P-DCS-Trace-Party-ID header is present 416 in a valid request, and contains an anonymous caller indication in 417 the name-addr parameter, the Originating Proxy MUST replace the 418 anonymous URL with the verified identify of the caller of the session 419 that is being traced if available and recorded by the proxy. 420 Otherwise, the proxy does not replace the anonymous URL. 422 If the origination proxy is provisioned to store URLs and target 423 dialog IDs for incoming calls, and if the proxy detects that the URL 424 and Target Dialog in a trace request does not match a recorded 425 incoming dialog request, then the proxy MUST reject the trace call 426 request. 428 The origination proxy does not add the P-DCS-Trace-Party-ID header 429 from a request that does not already contain the header. 431 5.6.2. Procedures at Terminating Proxy 433 This header MUST NOT appear in any request or response sent by a 434 terminating proxy to an untrusted endpoint. 436 6. P-DCS-OSPS 438 Some calls have special call processing requirements that may not be 439 satisfied by normal user agent call processing. For example, when a 440 user is engaged in a call and another call arrives, such a call might 441 be rejected with a busy indication. However, some PSTN operator 442 services require special call processing. In particular, the Busy 443 Line Verification (BLV) and Emergency Interrupt (EI) services 444 initiated by an operator from an Operator Services Position System 445 (OSPS) on the PSTN network have such a need. Similarly, emergency 446 calls to a 9-1-1 Public Service Access Point (PSAP) may result in 447 trunk signaling causing operator ringback using a howling tone or 448 sustained ring on the originating line (country-specific variations 449 may exist). 451 In order to inform the SIP user agent that special treatment should 452 be given to a call, we use a new P-DCS-OSPS header, with a field 453 which may be set to a value indicating when a special type of call 454 processing is requested. We define three values in this header 455 field, namely "BLV" for busy line verification, "EI" for emergency 456 interrupt, and "RING" for operator ringback (e.g., howling/sustained 457 tone ring in the US). 459 If the user agent decides to honor such a request, the response of 460 the user agent to an INVITE with either "BLV" or "EI" will not be a 461 busy indication. Since "EI" and "RING" only occur on established 462 dialogs, they may also appear in UPDATE requests. 464 6.1. Syntax 466 The ABNF description of the P-DCS-OSPS header is as follows (some 467 terms used in this ABNF are defined in [RFC3261]): 469 P-DCS-OSPS = "P-DCS-OSPS" HCOLON OSPS-Tag 470 OSPS-Tag = "BLV" / "EI" / "RING" / token 472 This document adds the following entry to Table 2 of [RFC3261]: 474 Header field where proxy ACK BYE CAN INV OPT REG PUB 475 ------------ ----- ----- --- --- --- --- --- --- --- 476 P-DCS-OSPS R dr - - - o - - - 477 SUB NOT REF INF UPD PRA MSG 478 --- --- --- --- --- --- --- 479 - - - - o - - 481 The OSPS-Tag value of "token" is defined for extensibility, and is 482 reserved for future use. 484 6.2. Procedures at an Untrusted User Agent Client (UAC) 486 The P-DCS-OSPS header MUST NOT be sent in a request from an untrusted 487 UAC. 489 6.3. Procedures at a Trusted User Agent Client (UAC) 491 This header is typically only inserted by a Media Gateway Controller 492 [DCSARCH] that is controlling a Media Gateway with special trunks to 493 a PSTN OSPS system or PSAP. This trunk group is usually referred to 494 as a BLV-trunk group and employs special signaling procedures that 495 prevent inadvertent use. Calls originating at the PSTN OSPS system 496 are sent over this trunk group, and result in an INVITE request with 497 the P-DCS-OSPS header. 499 This header MAY be sent in an INVITE request, and MUST NOT appear in 500 any message other than those listed below. 502 OSPS-Tag value "BLV" MUST NOT appear in any request other than an 503 initial INVITE request establishing a new dialog. 505 OSPS-Tag value "EI" MUST NOT appear in any request or response other 506 than (1) a subsequent INVITE within a pre-existing dialog established 507 with the OSPS-Tag value of "BLV", or (2) an UPDATE request within a 508 pre-existing dialog established with the OSPS-Tag value of "BLV". 510 OSPS-Tag value "RING" MUST NOT appear in any request or response 511 other than (1) a subsequent INVITE within a pre-existing dialog 512 established by a UAC to an operator or PSAP, or (2) an UPDATE request 513 within a pre-existing dialog established by a UAC to an operator or 514 PSAP. 516 6.4. Procedures at an Untrusted User Agent Server (UAS) 518 If the UAS receives an INVITE request with an OSPS-Tag of "BLV", 519 dialog identification that matches an existing dialog, it MUST reject 520 the request with a 403-Forbidden error code. 522 If the UAS receives an INVITE/UPDATE request with an OSPS-Tag value 523 of "EI" or "RING", with dialog identification that does not match an 524 existing dialog which was established with the OSPS-Tag value of 525 "BLV", it MUST reject the request with a 403-Forbidden response code. 527 If the UAS receives an INVITE that contains an OSPS-Tag value of 528 "BLV" and is not willing to cooperate in offering this service, it 529 MUST reject the request with a 403-Forbidden response code. 531 The UAS SHOULD NOT reject an INVITE with a BLV OSPS-Tag due to a busy 532 condition. The UAS MUST NOT respond with a 3xx-Redirect response 533 code to an INVITE with a BLV OSPS-Tag. The UAS SHOULD NOT alert the 534 user of the incoming call attempt if the BLV OSPS-Tag is present in 535 the INVITE. 537 If an INVITE with OSPS-Tag of "BLV" is accepted (e.g., meeting all 538 QoS pre-conditions, etc.), the UAS MUST send an audio stream on this 539 connection to the address and port given in the SDP of the INVITE. 540 The UAS MAY perform a mixing operation between the two ends of an 541 existing active call and send the resulting media stream to the 542 address and port indicated. Alternatively, the UAS MAY send a copy 543 of the local voice stream, and (if no activity on the local voice 544 stream) send a copy of the received voice stream of an existing call. 545 If the state of the UAS is idle, the UAS SHOULD send a stream of 546 silence packets to OSPS. If the state of the UAS is ringing or 547 ringback, the UAS SHOULD send a ringback stream to OSPS. 549 If an INVITE/UPDATE with OSPS-Tag of "EI" is accepted, the UAS MUST 550 enable communication between the UAC and the local user. The UAS MAY 551 put any existing call on hold, or initiate an ad-hoc conference. 553 If an INVITE/UPDATE with OSPS-Tag of "RING" is accepted, the UAS MUST 554 perform operator ringback in accordance with local procedures, e.g., 555 generate a 3-second howling tone or a sustained ring, depending on 556 the state of the user equipment. 558 6.5. Procedures at a Trusted User Agent Server (UAS) 560 The procedures at a trusted UAS MUST be identical to those described 561 in 6.4. 563 6.6. Procedures at Proxy 565 In the DCS architecture, the OSPS is considered a trusted UAC. If a 566 proxy receives a P-DCS-OSPS header in a request from an untrusted 567 source, it MUST either remove the header or reject the request with a 568 403-Forbidden response. 570 A proxy that implements a call-forwarding service MUST NOT respond to 571 an INVITE request with a 3xx response, if the request contained the 572 P-DCS-OSPS header. 574 7. P-DCS-BILLING-INFO 576 There are many billing models used in deriving revenue from telephony 577 services today. Charging for telephony services is tightly coupled 578 to the use of network resources. It is outside the scope of this 579 document to discuss the details of these numerous and varying 580 methods. 582 Proxies have access to subscriber information and act as policy 583 decision points and trusted intermediaries along the call signaling 584 path. Edge routers provide the network connection and resource 585 policy enforcement mechanism and also capture and report network 586 connection and resource usage information. Edge routers need to be 587 given billing information that can be logged with Record Keeping or 588 Billing servers. The proxy, as a central point of coordination 589 between call signaling and resource management, can provide this 590 information based on the authenticated identity of the calling and 591 called parties. Since there is a trust relationship among proxies, 592 they can be relied upon to exchange trusted billing information 593 pertaining to the parties involved in a call. 595 For Usage Accounting records, it is necessary to have an identifier 596 that can be associated with all the event records produced for the 597 call. The SIP Call-ID header field cannot be used as such an 598 identifier since it is selected by the originating user agent, and 599 may not be unique among all past calls as well as current calls. 600 Further, since this identifier is to be used by the service provider, 601 it should be chosen in a manner and in a format that meets the 602 service provider's needs. 604 Billing information may not necessarily be unique for each user 605 (consider the case of calls from an office all billed to the same 606 account). Billing information may not necessarily be identical for 607 all calls made by a single user (consider prepaid calls, credit card 608 calls, collect calls, etc). It is therefore necessary to carry 609 billing information separate from the calling and called party 610 identification. Furthermore, some billing models call for split- 611 charging where multiple entities are billed for portions of the call. 613 The addition of a SIP General Header Field allows for the capture of 614 billing information and billing identification for the duration of 615 the call. 617 It is the intent that the billing extensions would only appear on 618 trusted network segments, and MAY be inserted by a proxy or trusted 619 UA in INVITE and SUBSCRIBE requests in a trusted network segment, and 620 removed before leaving trusted network segments. The P-DCS-Billing- 621 Info header extension is used only on requests and responses between 622 proxies and trusted User Agents. It is never sent to an untrusted 623 UA. It is expected that untrusted UAs do not send this header. 625 7.1. Syntax 627 The DCS-Billing-Info header is defined by the following ABNF (some 628 terms used in this ABNF are defined in [RFC3261]): 630 P-DCS-Billing-Info = "P-DCS-Billing-Info" HCOLON 631 Billing-Correlation-ID "/" FEID 632 *(SEMI Billing-Info-param) 633 Billing-Correlation-ID = 1*48(HEXDIG) 634 FEID = 1*16(HEXDIG) "@" host 635 Billing-Info-param = RKS-Group-ID-param / Charge-param / 636 Calling-param / Called-param / 637 Routing-param / Loc-Routing-param / 638 JIP-param / generic-param 639 RKS-Group-ID-param = "rksgroup" EQUAL RKS-Group-ID 640 RKS-Group-ID = token 641 Charge-param = "charge" EQUAL Acct-Charge-URI 642 Acct-Charge-URI = LDQUOT addr-spec RDQUOT 643 Calling-param = "calling" EQUAL Acct-Calling-URI 644 Acct-Calling-URI = LDQUOT addr-spec RDQUOT 645 Called-param = "called" EQUAL Acct-Called-URI 646 Acct-Called-URI = LDQUOT addr-spec RDQUOT 647 Routing-param = "routing" EQUAL Acct-Routing-URI 648 Acct-Routing-URI = LDQUOT addr-spec RDQUOT 649 Loc-Routing-param = "locroute" EQUAL Acct-Loc-Routing-URI 650 Acct-Loc-Routing-URI = LDQUOT addr-spec RDQUOT 651 JIP-param = "jip" EQUAL jip 652 jip = LDQUOT 1*phonedigit-hex jip-context RDQUOT 653 jip-context = ";jip-context=" jip-descriptor 654 jip-descriptor = global-hex-digits 655 global-hex-digits = "+" 1*3(phonedigit) *phonedigit-hex 656 phonedigit = DIGIT / [ visual-separator ] 657 phonedigit-hex = HEXDIG / "*" / "#" / [ visual-separator ] 658 visual-separator = "-" / "." / "(" / ")" 660 This document adds the following entry to Table 2 of [RFC3261]: 662 Header field where proxy ACK BYE CAN INV OPT REG PUB 663 ------------ ----- ----- --- --- --- --- --- --- --- 664 P-DCS-Billing-Info admr - - - o - - - 666 SUB NOT REF INF UPD PRA MSG 667 --- --- --- --- --- --- --- 668 - - - - - - - 670 The P-DCS-Billing-Info extension contains an identifier that can be 671 used by an event recorder to associate multiple usage records, 672 possibly from different sources, with a billable account. It further 673 contains the subscriber account information, and other information 674 necessary for accurate billing of the service. This header is only 675 used between proxies and trusted User Agents. 677 The Billing-Correlation-ID, BCID, is specified in [PCEM] as a 24-byte 678 binary structure, containing 4 bytes of NTP timestamp, 8 bytes of the 679 unique identifier of the network element that generated the ID, 8 680 bytes giving the time zone, and 4 bytes of monotonically increasing 681 sequence number at that network element. This identifier is chosen 682 to be globally unique within the system for a window of several 683 months. This MUST be encoded in the P-DCS-Billing-Info header as a 684 hexadecimal string of up to 48 characters. Leading zeroes MAY be 685 suppressed. 687 The Financial-Entity-ID (FEID) is specified in [PCEM] as an 8-byte 688 structure, containing the financial identifier for that domain, 689 followed by a domain name. FEID can be associated with a type of 690 service and could be assigned to multiple domains by the same 691 provider. A domain could contain multiple assigned FEIDs. This 8- 692 byte structure MUST be encoded in the P-DCS-Billing-Info header as a 693 hexadecimal string of up to 16 characters. Trailing zeroes MAY be 694 suppressed. "Host" contains the domain name. 696 The RKS-Group-ID specifies a record keeping server (or group of 697 cooperating servers) for event messages relating to this call. It is 698 used to control certain optimizations of procedures when multiple 699 event message streams are being sent to the same Record Keeping 700 Server. 702 Additional parameters contain the information needed for generation 703 of event message records. Acct-Charge-URI, Acct-Calling-URI, Acct- 704 Called-URI, Acct-Routing-URI, and Acct-Loc-Routing-URI are each 705 defined as URLs; they should all contain tel URLs with E.164 706 formatted addresses. These fields are further defined in [PCEM] 707 under the element identifiers "Charge_Number" (element ID 16), 708 "Calling_Party_Number" (element ID 4), "Called_Party_Number" (element 709 ID 5), "Routing Number" (element ID 25), and 710 "Location_Routing_Number" (element ID 22). 712 The JIP-param contains the calling jurisdiction information, or 713 numbering plan area, of the network in which the call originated. 714 The field is further defined in [PCEM] under the element identifier 715 "Jurisdiction_Information_Parameter" (element ID 82). An older 716 [RFC3603] compliant implementation may not use the JIP-param. 718 7.2. Procedures at an Untrusted User Agent Client (UAC) 720 This header is never sent to an untrusted UA. It is expected that 721 untrusted UAs do not send this header. 723 7.3. Procedures at a Trusted User Agent Client (UAC) 725 The UAC MUST generate the Billing-Correlation-ID for the call, and 726 insert it into the P-DCS-Billing-Info header in the initial INVITE or 727 SUBSCRIBE message sent to the terminating entity, along with the 728 charging information for the call. The UAC MUST include its FEID, 729 and the RKS-Group-ID for the Record-Keeping-Server being used by the 730 UAC. If the UAC performed a Local Number Portability (LNP) query, it 731 MUST include the Routing Number and Location Routing Number returned 732 by the query. If available to the UAC, the UAC MUST include the JIP- 733 param. 735 If the response to the initial INVITE is a 3xx-Redirect, the UAC 736 generates a new initial INVITE request to the destination specified 737 in the Contact header field, as per standard SIP. If a UAC receives 738 a 3xx-Redirect response to an initial INVITE, the new INVITE 739 generated by the UAC MUST contain the P-DCS-Billing-Info header field 740 values from the 3xx- Redirect response. If the UAC is acting as a 741 B2BUA, instead of generating a new INVITE it MAY generate a private- 742 URL and place it in the Contact header field of a 3xx-Redirect 743 response sent to the originating endpoint. This private-URL MUST 744 contain (or contain a pointer to) the P-DCS-Billing-Info value, which 745 indicates the charging arrangement for the new call, and an 746 expiration time very shortly in the future, to limit the ability of 747 the originator to re-use this private-URL for multiple calls. 749 A UAC that includes a Refer-To header in a REFER request MUST include 750 a P-DCS-Billing-Info header in the Refer-To's URL. This P-DCS- 751 Billing-Info header MUST include the accounting information of the 752 initiator of the REFER. 754 7.4. Procedures at an Untrusted User Agent Server (UAS) 756 This header is never sent to an untrusted UAS, and is never sent by 757 an untrusted UAS. 759 7.5. Procedures at a Trusted User Agent Server (UAS) 761 The UAS MUST include a P-DCS-Billing-Info header in the first 762 reliable 1xx (except 100) or 2xx response to an initial INVITE or 763 SUBSCRIBE message. This P-DCS-Billing-Info header MUST include the 764 Billing- Correlation-ID generated by the UAS, the FEID of the UAS, 765 and the RKS-Group-ID of the Record-Keeping-Server being used by the 766 UAS. The UAS MAY change the values of Acct-Charge-URI if it wishes 767 to override the billing information that was present in the INVITE 768 (e.g., for a toll-free call). The decision to do this and the 769 contents of the new Acct-Charge-URI MUST be determined by service 770 provider policy provisioned in the UAS. If the UAS performed a LNP 771 query, it MUST include the Routing Number and Location Routing Number 772 returned by the query. 774 The UAS MUST add a P-DCS-Billing-Info header to a 3xx-redirect 775 response to an initial INVITE, giving the accounting information for 776 the call forwarder, for the call segment from the destination to the 777 forwarded-to destination. 779 7.6. Procedures at Proxy 781 Three sets of proxy procedures are defined: (1) the procedures at an 782 originating proxy, (2) the procedures at a terminating proxy, and (3) 783 the procedures at a tandem proxy. 785 The originating proxy is a proxy that received the INVITE or 786 SUBSCRIBE request from a non-trusted endpoint. 788 The terminating proxy is a proxy that sends the INVITE or SUBSCRIBE 789 request to a non-trusted endpoint. 791 A proxy that is neither an originating proxy, nor a terminating 792 proxy, is a tandem proxy. 794 For purposes of mid-call changes, such as call transfers, the proxy 795 that receives the request from a non-trusted endpoint is considered 796 the initiating proxy; the proxy that sends the request to a non- 797 trusted endpoint is considered the recipient proxy. Procedures for 798 the initiating proxy are included below with those for originating 799 proxies, while procedures for the recipient proxy are included with 800 those for terminating proxies. 802 A proxy that both receives the request from an untrusted endpoint, 803 and sends the request to a non-trusted endpoint, performs both sets 804 of procedures. 806 7.6.1. Procedures at Originating Proxy 808 The originating proxy MUST generate the Billing-Correlation-ID for 809 the call, and insert it into the P-DCS-Billing-Info header in the 810 initial INVITE or SUBSCRIBE message sent to the terminating entity, 811 along with the charging information for the call. The originating 812 proxy MUST include its FEID, and the RKS-Group-ID for the Record- 813 Keeping-Server being used by the originating proxy. If the 814 originating proxy performed a LNP query, it MUST include the Routing 815 Number, Location Routing Number and JIP-param returned by the query. 816 Any P-DCS-Billing-Info header present from an untrusted UA MUST be 817 removed. 819 If the Request-URI contains a private-URL, and the decoded username 820 contains billing information, the originating proxy MUST generate a 821 P-DCS-Billing-Info header with that decrypted information. 822 Otherwise, the originating proxy MUST determine the accounting 823 information for the call originator, and insert a P-DCS-Billing-Info 824 header including that information. 826 If the response to the initial INVITE is a 3xx-Redirect, received 827 prior to a non-100 provisional response, the originating proxy 828 generates a new initial INVITE request to the destination specified 829 in the Contact header field, as per standard SIP. If an originating 830 proxy receives a 3xx-Redirect response to an initial INVITE prior to 831 a non-100 provisional response, the INVITE generated by the proxy 832 MUST contain the P-DCS-Billing-Info header from the 3xx-Redirect 833 response. 835 If the response to the initial INVITE is a 3xx-Redirect, received 836 after a non-100 provisional response, the originating proxy generates 837 a private-URL and places it in the Contact header of a 3xx-Redirect 838 response sent to the originating endpoint. This private-URL MUST 839 contain (or contain a pointer to) the P-DCS-Billing-Info value, which 840 indicate the charging arrangement for the new call, and an expiration 841 time very shortly in the future, to limit the ability of the 842 originator to re-use this private-URL for multiple calls. 844 An originating proxy that processes a REFER request from an untrusted 845 UA MUST include a P-DCS-Billing-Info header in the Refer-To's URL. 846 This P-DCS-Billing-Info header MUST include the accounting 847 information of the initiator. 849 7.6.2. Procedures at Terminating Proxy 851 The terminating proxy MUST NOT send the P-DCS-Billing-Info header to 852 an untrusted destination. 854 The terminating proxy MUST include a P-DCS-Billing-Info header in the 855 first reliable 1xx (except 100) or 2xx response to an initial INVITE 856 or SUBSCRIBE message. This P-DCS-Billing-Info header MUST include 857 the Billing-Correlation-ID generated by the terminating proxy, the 858 FEID of the terminating proxy, and the RKS-Group-ID of the Record- 859 Keeping-Server being used by the terminating proxy. The terminating 860 proxy MAY change the values of Acct-Charge-URI if it wishes to 861 override the billing information that was present in the INVITE 862 (e.g., for a toll-free call). The decision to do this and the 863 contents of the resulting P-DCS-Billing-Info header MUST be 864 determined by service provider policy provisioned in the terminating 865 proxy. If the terminating proxy performed a LNP query, it MUST 866 include the Routing Number and Location Routing Number returned by 867 the query. 869 The terminating proxy MUST add P-DCS-Billing-Info headers to a 3xx- 870 redirect response to an initial INVITE, giving the accounting 871 information for the call forwarder, for the call segment from the 872 destination to the forwarded-to destination. 874 A proxy receiving a mid-call REFER request that includes a Refer-To 875 header generates a private-URL and places it in the Refer-To header 876 sent to the endpoint. This private-URL MUST contain the P-DCS- 877 Billing-Info value, which indicates the charging arrangement for the 878 new call, and an expiration time very shortly in the future, to limit 879 the ability of the endpoint to re-use this private-URL for multiple 880 calls. 882 7.6.3. Procedures at Tandem Proxy 884 If the tandem proxy performed a LNP query, it MUST insert the Routing 885 Number and Location Routing Number returned by the query into the P- 886 DCS-Billing-Info header in the first reliable 1xx/2xx/3xx (except 887 100) response. 889 8. P-DCS-LAES and P-DCS-Redirect 891 NOTE: According to RFC 2804 [RFC2804], the IETF supports 892 documentation of lawful intercept technology if it is necessary to 893 develop it. The following section provides such documentation. The 894 [RFC2119] language, as stated above, describes the requirements of 895 the specification only if implemented, and strictly within the 896 applicability domain described above. See RFC 2804 for description 897 of issues regarding privacy, security, and complexity in relation to 898 this technology. 900 The P-DCS-LAES extension contains the information needed to support 901 Lawfully Authorized Electronic Surveillance. This header contains 902 the address and port of an Electronic Surveillance Delivery Function 903 for delivery of a duplicate stream of event messages related to this 904 call. The header fields MAY also contain the associated BCID for the 905 event stream as well as additional address and port for delivery of 906 call content and associated cccid. The BCID is used to correlate a 907 series of events associated with a single call or session. The cccid 908 is used to identify an intercepted call content to an intercepted 909 call. The P-DCS-LAES header is only used between proxies and trusted 910 User Agents. The P-DCS-LAES header defined here is not backwards 911 compatible with that defined in [RFC3603], which is deprecated by the 912 document. This version of the P-DCS-LAES header adds a ccc-id 913 parameter to support the intercept of content, and deletes security 914 key information. This version does not mandate the use of the BCID. 916 The P-DCS-Redirect extension contains call identifying information 917 needed to support the requirements of Lawfully Authorized Electronic 918 Surveillance of redirected calls. This header is only used between 919 proxies and trusted User Agents. 921 Note that there is overlap in function between the P-DCS-Redirect 922 header and the History-Info header specified in RFC 4244. The 923 original P-DCS-Redirect came to existence in RFC 3603 before the 924 History-Info. Therefore, the P-DCS-Redirect header is continued here 925 for backward compatibility with existing implementations. 927 Use of P-DCS-LAES and P-DCS-Redirect is controlled by a combination 928 of legislation, regulation, and court orders, which MUST be followed. 929 In certain cases inclusion of these headers will be mandated, and 930 therefore MUST be present in the requests and responses indicated. 931 In other cases inclusion of these headers will be forbidden, and 932 therefore MUST NOT be present in the request and responses indicated. 933 In the sub-sections that follow, use of "SHOULD" is intended to 934 capture these conflicting situations, e.g., a P-DCS-LAES header 935 SHOULD be included in an initial INVITE means either that it MUST be 936 included or that it MUST NOT be included, based on the applicable 937 court orders. 939 8.1. Syntax 941 The formats of the P-DCS-LAES and P-DCS-Redirect headers are given by 942 the following ABNF (some terms used in this ABNF are defined in 943 [RFC3261] and [RFC5234]): 945 P-DCS-LAES = "P-DCS-LAES" HCOLON Laes-sig 946 *(SEMI Laes-param) 947 Laes-sig = hostport 948 Laes-param = Laes-content / Laes-cccid 949 Laes-bcid / generic-param 950 Laes-content = "content" EQUAL hostport 952 Laes-bcid = "bcid" EQUAL 1*48(HEXDIG) 953 Laes-cccid = "cccid" EQUAL 1*8(HEXDIG) 955 P-DCS-Redirect = "P-DCS-Redirect" HCOLON Called-ID 956 *(SEMI redir-params) 957 Called-ID = LDQUOT addr-spec RDQUOT 958 redir-params = redir-uri-param / redir-count-param / 959 generic-param 960 redir-uri-param = "redirector-uri" EQUAL Redirector 961 Redirector = LDQUOT addr-spec RDQUOT 962 redir-count-param = "count" EQUAL Redir-count 963 Redir-count = 1*DIGIT 965 This document adds the following entry to Table 2 of [RFC3261]: 966 Header field where proxy ACK BYE CAN INV OPT REG PUB 967 ------------ ----- ----- --- --- --- --- --- --- --- 968 P-DCS-LAES adr - - - o - - - 969 P-DCS-Redirect adr - - - o - - - 971 SUB NOT REF INF UPD PRA MSG 972 --- --- --- --- --- --- --- 973 - - - - - - - 974 - - - - - - - 976 The values of Laes-sig and Laes-content are addresses of the 977 Electronic Surveillance Delivery Function, and used as the 978 destination address for call-identifying information and call- 979 content, respectively. Laes-bcid contains a correlation ID that is 980 used to link a sequence of intercepted call processing events related 981 to a single call. Laes-cccid contains an identifier of the 982 intercepted call content. The Laes-bcid field MAY be present. The 983 BCID is included per network operator configuration to support events 984 reported as defined in [PCEM]. The Laes-cccid field MAY be present 985 when the Laes-content field is present. The Laes-cccid is included 986 per network operator configuration for networks where entities 987 receiving the intercepted contents may act a media relay functions to 988 other surveillance functions that are the source of the content 989 surveillance request. The design of multiple surveillance entities 990 that receive call content is beyond the scope of this document. 992 The P-DCS-Redirect header contains redirection information. The 993 Called-ID indicates the original destination requested by the user 994 (e.g., number dialed originally), the redir-uri-param indicates the 995 entity performing the redirection, and the Redir-count indicates the 996 number of redirections that have occurred. For example, if A calls 997 B, who forwards to C, who forwards to D, then, when C forwards to D, 998 the Called-ID will be A, redir-uri-param will be C, and count will be 999 2. 1001 8.2. Procedures at an Untrusted User Agent Client (UAC) 1003 This header MUST NOT be sent to an untrusted UAC, and MUST NOT be 1004 sent by an untrusted UAC. 1006 8.3. Procedures at a Trusted User Agent Client (UAC) 1008 The UAC checks for an outstanding lawfully authorized surveillance 1009 order for the originating subscriber, and, if present, MAY include 1010 this information in the Authorization for Quality of Service [PCDQOS] 1011 or MAY signal this information to the device performing the intercept 1012 (e.g., a Media Gateway). Otherwise, intercept access points are 1013 instructed to perform call content and/or call data intercept by 1014 mechanisms that are outside the scope of this document. 1016 If the P-DCS-LAES header is present in the first reliable 1xx (except 1017 100), 2xx or 3xx response (indicating surveillance is required on the 1018 terminating subscriber, but that the terminating equipment is unable 1019 to perform that function), the UAC MAY include this information in 1020 the Authorization for Quality of Service, or MAY signal this 1021 information to the device performing the intercept (e.g., a Media 1022 Gateway). Otherwise, intercept access points are instructed to 1023 perform call content and/or call data intercept by mechanisms that 1024 are outside the scope of this document. 1026 If a 3xx-Redirect response is received to the initial INVITE request, 1027 and if a P-DCS-LAES header is present in the 3xx response, the UAC 1028 SHOULD include that header unchanged in the reissued INVITE. The UAC 1029 SHOULD also include a P-DCS-Redirect header containing the original 1030 dialed number, the most recent redirecting party, and the number of 1031 redirections that have occurred. Although it is technically possible 1032 for the originating equipment to perform this surveillance (or add to 1033 its existing surveillance of the call), the design of the 1034 surveillance system has the terminating equipment performing the 1035 surveillance for all the intermediate forwardings. 1037 A UAC that includes a Refer-To header in a REFER request, when the 1038 originating subscriber has an outstanding lawfully authorized 1039 surveillance order, SHOULD include a P-DCS-LAES header attached to 1040 the Refer-To. The UAC may also include a P-DCS-Redirect header. The 1041 P-DCS-LAES header MAY include the Laes-bcid parameter set to a value 1042 that uniquely identifies the call, SHOULD include the address and 1043 port of the local Electronic Surveillance Delivery Function for a 1044 copy of the call's event messages, SHOULD include the address and 1045 port of the local Electronic Surveillance Delivery Function for the 1046 copy of call content if call content is to be intercepted, and MAY 1047 include the Laes-cccid parameter set to a value that uniquely 1048 identifies the intercepted audio stream if call content is to be 1049 intercepted. 1051 The trusted UAC MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1052 headers to an untrusted entity. 1054 8.4. Procedures at an Untrusted User Agent Server (UAS) 1056 This header MUST NOT be sent to an untrusted UAS, and MUST NOT be 1057 sent by an untrusted UAS. 1059 8.5. Procedures at a Trusted User Agent Server (UAS) 1061 The UAS checks for an outstanding lawfully authorized surveillance 1062 order for the terminating subscriber, or presence of the P-DCS-LAES 1063 header in the INVITE request. If either is present, the UAS MAY 1064 include this information in the authorization for Quality of Service 1065 [PCDQOS].Otherwise, intercept access points are instructed to perform 1066 call content and/or call data intercept by mechanisms that are 1067 outside the scope of this document. 1069 If the terminating equipment is unable to perform the required 1070 surveillance (e.g., if the destination is a voicemail server), the 1071 UAS SHOULD include a P-DCS-LAES header in the first reliable 1xx 1072 (except 100), 2XX or 3XX response requesting the originating proxy to 1073 perform the surveillance. The P-DCS-LAES header MAY include the 1074 Laes-bcid parameter with a value that uniquely identifies the call, 1075 SHOULD include the address and port of the local Electronic 1076 Surveillance Delivery Function for a copy of the call's event 1077 messages, SHOULD include the address and port of the local Electronic 1078 Surveillance Delivery Function for the copy of call content if call 1079 content is to be intercepted, and MAY include the Laes-cccid 1080 parameter set to a value that uniquely identifies the intercepted 1081 audio stream if call content is to be intercepted. 1083 If the response to the initial INVITE request is a 3xx-Redirect 1084 response, and there is an outstanding lawfully authorized 1085 surveillance order for the terminating subscriber, the UAS SHOULD 1086 include a P-DCS-LAES header in the 3xx-Redirect response, with 1087 contents as described above. 1089 The trusted UAS MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1090 headers to an untrusted entity. 1092 8.6. Procedures at Proxy 1094 Two sets of proxy procedures are defined: (1) the procedures at an 1095 originating proxy, and (2) the procedures at a terminating proxy. 1096 The originating proxy is a proxy that receives the INVITE request 1097 from a non-trusted endpoint. 1099 The terminating proxy is a proxy that sends the INVITE request to a 1100 non-trusted endpoint. 1102 For purposes of mid-call changes, such as call transfers, the proxy 1103 that receives the request from a non-trusted endpoint is considered 1104 the initiating proxy; the proxy that sends the request to a non- 1105 trusted endpoint is considered the recipient proxy. Procedures for 1106 the initiating proxy are included below with those for originating 1107 proxies, while procedures for the recipient proxy are included with 1108 those for terminating proxies. 1110 A proxy that both receives the INVITE request from an untrusted 1111 endpoint, and sends the INVITE request to a non-trusted endpoint, 1112 MUST NOT generate P-DCS-LAES nor P-DCS-Redirect headers. 1114 A proxy that is neither an originating proxy nor a terminating proxy 1115 SHOULD pass the P-DCS-Laes and P-DCS-Redirect headers in requests and 1116 responses. 1118 8.6.1. Procedures at Originating Proxy 1120 The Originating Proxy MUST remove any P-DCS-LAES and P-DCS-Redirect 1121 headers in requests or responses to or from an untrusted proxy or 1122 untrusted UA. 1124 The originating proxy checks for an outstanding lawfully authorized 1125 surveillance order for the originating subscriber, and, if present, 1126 MAY include this information in the Authorization for Quality of 1127 Service [PCDQOS] or MAY signal this information to the device 1128 performing the intercept (e.g., a Media Gateway). Otherwise, 1129 intercept access points are instructed to perform call content and/or 1130 call data intercept by mechanisms that are outside the scope of this 1131 document. 1133 If the P-DCS-LAES header is present in the first reliable 1xx (except 1134 100), 2xx or 3xx response (indicating surveillance is required on the 1135 terminating subscriber, but that the terminating equipment is unable 1136 to perform that function), the originating proxy MAY include this 1137 information in the Authorization for Quality of Service, or MAY 1138 signal this information to the device performing the intercept (e.g., 1139 a Media Gateway). Otherwise, intercept access points are instructed 1140 to perform call content and/or call data intercept by mechanisms that 1141 are outside the scope of this document. 1143 If the Request-URI in an initial INVITE request contains a private- 1144 URL, the originating proxy MUST decrypt the userinfo information to 1145 find the real destination for the call, and other special processing 1146 information. If electronic surveillance information is contained in 1147 the decrypted userinfo, the originating proxy SHOULD generate a P- 1148 DCS-LAES and (if necessary) a P-DCS-REDIRECT header with the 1149 surveillance information. 1151 If a 3xx-Redirect response is received to the initial INVITE request 1152 prior to a non-100 provisional response, and if a P-DCS-LAES header 1153 is present in the 3xx response, the originating proxy SHOULD include 1154 that header unchanged in the reissued INVITE. The originating proxy 1155 SHOULD also include a P-DCS-Redirect header containing the original 1156 dialed number, the most recent redirecting party, and the number of 1157 redirections that have occurred. 1159 If a 3xx-Redirect response is received to the initial INVITE request 1160 after a non-100 provisional response, the originating proxy generates 1161 a private-URL and places it in the Contact header of a 3xx-Redirect 1162 response sent to the originating endpoint. If a P-DCS-LAES header is 1163 present in the 3xx response, this private-URL MUST contain (1) the 1164 electronic surveillance information from the 3xx-Redirect response, 1165 (2) the original destination number, (3) the identity of the 1166 redirecting party, and (4) the number of redirections of this call. 1168 An originating proxy that processes a REFER request [RFC3515] from an 1169 untrusted UA, when the originating subscriber has an outstanding 1170 lawfully authorized surveillance order, becomes a B2BUA for that 1171 request. It SHOULD reissue the request with a P-DCS-LAES header 1172 added to the Refer-To's URL. It MAY also include a P-DCS-Redirect 1173 header. The P-DCS-LAES header SHOULD include (1) the address and 1174 port of the local Electronic Surveillance Delivery Function for a 1175 copy of the call's event messages, (2) the address and port of the 1176 local Electronic Surveillance Delivery Function for the copy of call 1177 content if call content is to be intercepted. The P-DCS-LAES header 1178 MAY include (1) the Laes-bcid parameter set to a value that uniquely 1179 identifies the call, and (2) the Laes-cccid parameter set to a value 1180 that uniquely identifies the intercepted audio stream if call content 1181 is to be intercepted. 1183 An initiating proxy that sends a mid-call REFER request including a 1184 Refer-to header, when the initiating subscriber has an outstanding 1185 lawfully authorized surveillance order, SHOULD include a P-DCS-LAES 1186 header in the Refer-To's URL. 1188 The originating proxy MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1189 headers to an untrusted entity. 1191 8.6.2. Procedures at Terminating Proxy 1193 The Terminating Proxy MUST remove any P-DCS-LAES and P-DCS-Redirect 1194 headers in requests or responses to or from an untrusted proxy or UA. 1196 The terminating proxy checks for an outstanding lawfully authorized 1197 surveillance order for the terminating subscriber. If present, the 1198 terminating proxy MAY include this information in the authorization 1199 for Quality of Service [PCDQOS]. Otherwise, intercept access points 1200 are instructed to perform call content and/or call data intercept by 1201 mechanisms that are outside the scope of this document. 1203 The terminating proxy MUST NOT send the P-DCS-LAES and P-DCS-Redirect 1204 headers to an untrusted entity, either as headers in the request or 1205 response, or as headers attached to URIs in the request or response. 1207 If the terminating equipment is unable to perform the required 1208 surveillance (e.g., if the destination is a voicemail server), the 1209 terminating proxy SHOULD include a P-DCS-LAES header in the first 1210 reliable 1xx/2xx/3xx (except 100) response requesting the originating 1211 proxy to perform the surveillance. The P-DCS-LAES header MAY include 1212 the Laes-bcid parameter set to a value that uniquely identifies the 1213 call, SHOULD include the address and port of the local Electronic 1214 Surveillance Delivery Function for a copy of the call's event 1215 messages, SHOULD include the address and port of the local Electronic 1216 Surveillance Delivery Function for the copy of call content if call 1217 content is to be intercepted, and MAY include the Laes-cccid 1218 parameter set to a value that uniquely identifies the audio stream if 1219 call content is to be intercepted. 1221 If the response to the initial INVITE request is a 3xx-Redirect 1222 response, and there is an outstanding lawfully authorized 1223 surveillance order for the terminating subscriber, the terminating 1224 proxy SHOULD include a P-DCS-LAES header in the 3xx-Redirect 1225 response, with contents as described above. 1227 A proxy receiving a mid-call REFER request [RFC3515] that includes a 1228 Refer-To header with a P-DCS-LAES header attached becomes a B2BUA for 1229 this request. It MUST generate a private-URL and place it in the 1230 Refer-To header sent to the endpoint. This private-URL MUST contain 1231 the P-DCS-LAES and P-DCS-Redirect information from the attached 1232 header fields. 1234 9. Security Considerations 1236 QoS gate coordination, billing information, and electronic 1237 surveillance information are all considered to be sensitive 1238 information that MUST be protected from eavesdropping and furthermore 1239 require integrity checking. It is therefore necessary that the 1240 trusted UAs and proxies take precautions to protect this information 1241 from eavesdropping and tampering. Use of IPsec or TLS between 1242 Proxies and Trusted User Agents is REQUIRED. A minimum mandatory-to- 1243 implement IPsec configuration for the DCS architecture is given by 1244 [PCSEC]. Also REQUIRED is mutual authentication (1) between Proxies 1245 and (2) between trusted UAs and Proxies, both of which MAY be 1246 implemented with administratively pre-shared keys, or through 1247 consultation with another trusted third party. If IPsec is to be 1248 used, the specification of the security policies and procedures of 1249 the administrative domain where these headers are applicable (and all 1250 connections between administrative domains in the federation) MUST 1251 define an interoperable set of options. 1253 10. IANA Considerations 1255 The following changes to the Session Initiation Protocol (SIP) 1256 Parameters registry need be registered with IANA. . 1258 The header field registry is updated as follows: 1260 Header Name compact Reference 1261 ----------------- ------- --------- 1262 P-DCS-Trace-Party-ID [RFCxxxx] 1263 P-DCS-OSPS [RFCxxxx] 1264 P-DCS-Billing-Info [RFCxxxx] 1265 P-DCS-LAES [RFCxxxx] 1266 P-DCS-Redirect [RFCxxxx] 1268 The following entries in the Header Field Parameters and Parameter 1269 Values registry are updated as follows: 1271 Header Field Parameter Name Values 1272 Reference 1273 ---------------------------- --------------------------- ---------- 1275 P-DCS-Billing-Info called No 1276 [RFCxxxx] 1277 P-DCS-Billing-Info calling No 1278 [RFCxxxx] 1279 P-DCS-Billing-Info charge No 1280 [RFCxxxx] 1281 P-DCS-Billing-Info locroute No 1282 [RFCxxxx] 1283 P-DCS-Billing-Info rksgroup No 1284 [RFCxxxx] 1285 P-DCS-LAES content No 1286 [RFCxxxx] 1287 P-DCS-Redirect count No 1288 [RFCxxxx] 1289 P-DCS-Redirect redirector-uri No 1290 [RFCxxxx] 1292 The following new entries in the Header Field Parameters and 1293 Parameter Values registry are removed as follows: 1295 Header Field Parameter Name Values 1296 Reference 1297 ---------------------------- --------------------------- ---------- 1299 P-DCS-Billing-Info routing No 1300 [RFC3603] 1301 P-DCS-LAES key No 1302 [RFC3603] 1304 The following new entries in the Header Field Parameters and 1305 Parameter Values registry are created as follows: 1307 Header Field Parameter Name Values 1308 Reference 1309 ---------------------------- --------------------------- ---------- 1311 P-DCS-Billing-Info jip No 1312 [RFCxxxx] 1313 P-DCS-LAES bcid No 1314 [RFCxxxx] 1315 P-DCS-LAES cccid No 1316 [RFCxxxx] 1317 P-DCS-Trace-Party-ID timestamp No 1318 [RFCxxxx] 1320 11. Change Log 1322 o A timestamp parameter is added to the P-DCS-Trace-Party-ID header 1323 when available. Procedures on the use of the Target-Dialog header 1324 used together with the P-DCS-Trace-Party-ID are added. 1326 o The JIP parameter is added to the P-DCS-Billing-Infor header when 1327 available 1329 o The BCID billing correlation identifier and cccid call content 1330 channel identifier are addded to the P-DCS-LAES header. 1332 o P-DCS-Billing-Info header is applied to the SUBSCRIBE method. 1334 o P-DCS-REDIRECT header is applied to the REFER method. 1336 o The use of QoS authorization to establish content intercept is 1337 made optional in order not to preclude alternative content 1338 intercept provisioning mechanisms. 1340 o PUBLISH and MESSAGE methods are addded to the SIP method 1341 applicability matrices throughout. 1343 o Correction is made to table 2 to add m=modify. 1345 o IANA considerations are updated. 1347 o Corrections are made to timestamp format and references are 1348 updated. 1350 12. Acknowledgements 1352 The Distributed Call Signaling work in the PacketCable project is the 1353 work of a large number of people, representing many different 1354 companies. The authors would like to recognize and thank the 1355 following for their assistance: John Wheeler, Motorola; David 1356 Boardman, Daniel Paul, Arris Interactive; Bill Blum, Jon Fellows, Jay 1357 Strater, Jeff Ollis, Clive Holborow, Motorola; Doug Newlin, Guido 1358 Schuster, Ikhlaq Sidhu, 3Com; Jiri Matousek, Bay Networks; Farzi 1359 Khazai, Nortel; John Chapman, Bill Guckel, Michael Ramalho, Cisco; 1360 Chuck Kalmanek, Doug Nortz, John Lawser, James Cheng, Tung- Hai 1361 Hsiao, Partho Mishra, AT&T; Telcordia Technologies; and Lucent Cable 1362 Communications. 1364 Previous versions further acknowledged, as co-authors, several people 1365 for providing the text of this document. They are: 1367 Bill Marshall (wtm@research.att.com) and K. K. Ramakrishnan 1368 (kkrama@research.att.com), AT&T; Ed Miller 1369 (edward.miller@terayon.com), Terayon; David Hancock (D.Hancock@ 1370 Cablelabs.com) and Glenn Russell (G.Russell@Cablelabs.com), 1371 CableLabs; Burcak Beser (burcak@juniper.net) Juniper Networks, Mike 1372 Mannette (Michael_Mannette@3com.com) and Kurt Steinbrenner 1373 (Kurt_Steinbrenner@3com.com), 3Com; Dave Oran (oran@cisco.com) and 1374 Flemming Andreasen (fandreas@cisco.com), Cisco Systems; John Pickens 1375 (jpickens@com21.com), Com21; Poornima Lalwaney 1376 (poornima.lalwaney@nokia.com), Nokia; Jon Fellows 1377 (jfellows@coppermountain.com), Copper Mountain Networks; Doc Evans 1378 (n7dr@arrisi.com) Arris, Keith Kelly (keith@netspeak.com), NetSpeak, 1379 and Brian Lindsay, Nortel Networks. 1381 13. References 1383 13.1. Normative References 1385 [RFC1305] Mills, D., "Network Time Protocol (Version 3) 1386 Specification, Implementation", RFC 1305, March 1992. 1388 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1389 Requirement Levels", BCP 14, RFC 2119, March 1997. 1391 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 1392 A., Peterson, J., Sparks, R., Handley, M., and E. 1393 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 1394 June 2002. 1396 [RFC3515] Sparks, R., "The Session Initiation Protocol (SIP) Refer 1397 Method", RFC 3515, April 2003. 1399 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 1400 10646", STD 63, RFC 3629, November 2003. 1402 [RFC4330] Mills, D., "Simple Network Time Protocol (SNTP) Version 4 1403 for IPv4, IPv6 and OSI", RFC 4330, January 2006. 1405 [RFC4538] Rosenberg, J., "Request Authorization through Dialog 1406 Identification in the Session Initiation Protocol (SIP)", 1407 RFC 4538, June 2006. 1409 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 1410 Specifications: ABNF", STD 68, RFC 5234, January 2008. 1412 13.2. Informative References 1414 [DCSARCH] Marshall, W., Osman, M., Andreasen, F., and D. Evans, 1415 "Architectural Considerations for Providing Carrier Class 1416 Telephony Services Utilizing SIP-based Distributed Call 1417 Control Mechanisms", Jan 2003. 1419 [PCDQOS] Cable Television Laboratories, Inc., "PacketCable 1.5 1420 Specifications, Dynamic Quality of Service", Aug 2005. 1422 [PCEM] Cable Television Laboratories, Inc., "PacketCable 1.5 1423 Specifications, Event Messages", Dec 2005. 1425 [PCSEC] Cable Television Laboratories, Inc., "PacketCable 1.5 1426 Specifications, Security", Jan 2005. 1428 [RFC2804] IAB and IESG, "IETF Policy on Wiretapping", RFC 2804, 1429 May 2000. 1431 [RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private 1432 Extensions to the Session Initiation Protocol (SIP) for 1433 Asserted Identity within Trusted Networks", RFC 3325, 1434 November 2002. 1436 [RFC3603] Marshall, W. and F. Andreasen, "Private Session Initiation 1437 Protocol (SIP) Proxy-to-Proxy Extensions for Supporting 1438 the PacketCable Distributed Call Signaling Architecture", 1439 RFC 3603, October 2003. 1441 Authors' Addresses 1443 Flemming Andreasen 1444 Cisco 1445 Edison, NJ 1446 USA 1448 Email: fandreas@cisco.com 1450 Bernie McKibben 1451 CableLabs 1452 Louisville, CO 1453 USA 1455 Email: B.McKibben@cablelabs.com 1457 Bill Marshall 1458 AT&T 1459 Florham Park, NJ 1460 USA 1462 Email: wtm@research.att.com 1464 Full Copyright Statement 1466 Copyright (C) The IETF Trust (2008). 1468 This document is subject to the rights, licenses and restrictions 1469 contained in BCP 78, and except as set forth therein, the authors 1470 retain all their rights. 1472 This document and the information contained herein are provided on an 1473 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 1474 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 1475 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 1476 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 1477 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 1478 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1480 Intellectual Property 1482 The IETF takes no position regarding the validity or scope of any 1483 Intellectual Property Rights or other rights that might be claimed to 1484 pertain to the implementation or use of the technology described in 1485 this document or the extent to which any license under such rights 1486 might or might not be available; nor does it represent that it has 1487 made any independent effort to identify any such rights. 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