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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: '9' is defined on line 371, but no explicit reference was found in the text ** Obsolete normative reference: RFC 2141 (ref. '4') (Obsoleted by RFC 8141) ** Obsolete normative reference: RFC 4346 (ref. '5') (Obsoleted by RFC 5246) Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Dispatch Working Group A. Allen, Ed. 3 Internet-Draft Blackberry 4 Intended status: Informational February 26, 2014 5 Expires: August 30, 2014 7 Using the International Mobile station Equipment Identity (IMEI) 8 Uniform Resource Name (URN) as an Instance ID 9 draft-allen-dispatch-imei-urn-as-instanceid-13 11 Abstract 13 This specification specifies how the Uniform Resource Name (URN) 14 reserved for the GSMA (GSM Association) identities and its sub- 15 namespace for the IMEI (International Mobile station Equipment 16 Identity) can be used as an instance-id. Its purpose is to fulfil 17 the requirements for defining how a specific URN needs to be 18 constructed and used in the "+sip.instance" Contact header field 19 parameter for outbound behavior. 21 Status of this Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on August 30, 2014. 38 Copyright Notice 40 Copyright (c) 2014 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 4. 3GPP Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 5 63 5. User Agent Client Procedures . . . . . . . . . . . . . . . . . 6 65 6. User Agent Server Procedures . . . . . . . . . . . . . . . . . 7 67 7. 3GPP SIP Registrar Procedures . . . . . . . . . . . . . . . . . 7 69 8. IANA considerations . . . . . . . . . . . . . . . . . . . . . . 7 71 9. Security considerations . . . . . . . . . . . . . . . . . . . . 7 73 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 75 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 76 11.1. Normative references . . . . . . . . . . . . . . . . . . . 8 77 11.2. Informative references . . . . . . . . . . . . . . . . . . 9 79 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9 81 1. Introduction 83 This specification specifies how the Uniform Resource Name reserved 84 for GSMA identities and its sub-namespace for the IMEI (International 85 Mobile station Equipment Identity) as specified in 86 draft-montemurro-gsma-imei-urn-20 [1] can be used as an instance-id 87 as specified in RFC 5626 [2] and also as used by RFC 5627 [3]. 89 RFC 5626 [2] specifies the "+sip.instance" Contact header field 90 parameter that contains a URN as specified in RFC 2141 [4]. The 91 instance-id uniquely identifies a specific UA instance. This 92 instance-id is used as specified in RFC 5626 [2] so that the SIP 93 (Session Initiation Protocol) registrar (as specified in RFC 3261 94 [5]) can recognize that the contacts from multiple registrations 95 correspond to the same UA. The instance-id is also used as specified 96 by RFC 5627 [3] to create Globally Routable User Agent URIs (GRUUs) 97 that can be used to uniquely address a UA when multiple UAs are 98 registered with the same Address of Record (AoR). 100 RFC 5626 [2] requires that a UA SHOULD create a Universally Unique 101 Identifier (UUID) URN as specified in RFC 4122 [6] as its instance-id 102 but allows for the possibility to use other URN schemes. "If a URN 103 scheme other than UUID is used, the UA MUST only use URNs for which 104 an RFC (from the IETF stream) defines how the specific URN needs to 105 be constructed and used in the "+sip.instance" Contact header field 106 parameter for outbound behavior." This specification meets this 107 requirement by specifying how the GSMA IMEI URN is used in the 108 "+sip.instance" Contact header field parameter for outbound behavior, 109 and draft-montemurro-gsma-imei-urn-20 [1] specifies how the GSMA IMEI 110 URN is constructed. 112 The GSMA IMEI is a URN for the IMEI a globally unique identifier that 113 identifies mobile devices used in the Global System for Mobile 114 communications(GSM), Universal Mobile Telecommunications System 115 (UMTS) and 3GPP LTE (Long Term Evolution)networks. The IMEI 116 allocation is managed by the GSMA to ensure that the IMEI values are 117 globally unique. Details of the formatting of the IMEI as a URN are 118 specified in draft-montemurro-gsma-imei-urn-20 [1] and the definition 119 of the IMEI is contained in 3GPP TS 23.003 [10]. Further details 120 about the GSMA role in allocating the IMEI and the IMEI allocation 121 guidelines can be found in GSMA PRD TS.06 [11]. 123 2. Terminology 125 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 126 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 127 document are to be interpreted as described in RFC 2119 [7]. 129 3. Background 131 GSM, UMTS and LTE capable mobile devices represent 90% of the mobile 132 devices in use worldwide. Every manufactured GSM, UMTS or LTE mobile 133 device has an allocated IMEI that uniquely identifies this specific 134 mobile device. Amongst other things in some regulatory jurisdictions 135 the IMEI is used to identify that a stolen mobile device is being 136 used, to help to identify the subscription that is using it and to 137 prevent use of the mobile device. Whilst GSM was originally a 138 circuit switched system, enhancements such as GPRS (General Packet 139 Radio Service) and UMTS have added IP data capabilities which along 140 with the definition of the IP (Internet Protocol) Multimedia 141 Subsystem (IMS) have made SIP based calls and IP multimedia sessions 142 from mobile devices possible. 144 The latest enhancement known as LTE introduces even higher data rates 145 and dispenses with the circuit switched infrastructure completely. 146 This means that with LTE networks, voice calls will need to be 147 conducted using IP and IMS. However, the transition to all IP, SIP 148 based IMS networks worldwide will take a great many years and mobile 149 devices being mobile will need to operate in both IP/SIP/IMS mode and 150 circuit switched mode. This means that calls and sessions will need 151 to be handed over between IP/SIP/IMS mode and circuit switched mode 152 mid-call or mid-session. Also since many existing GSM and UMTS radio 153 access networks are unable to support IP/SIP/IMS based voice services 154 in a commercially acceptable manner, some sessions could have some 155 media types delivered via IP/IMS simultaneously with voice media 156 delivered via the circuit switched domain to the same mobile device. 157 To achieve this the mobile device is needs to be simultaneously 158 attached via both the IP/SIP/IMS domain and the circuit switched 159 domain. 161 To meet this need 3GPP has specified how to maintain session 162 continuity between the IP/SIP/IMS domain and the circuit switched 163 domain in 3GPP TS 24.237 [12] and how to access IMS hosted services 164 via both the IP/SIP/IMS domain and the circuit switched domain in 165 3GPP TS 24.292 [13]. 167 In order for the mobile device to access SIP/IMS services via the 168 circuit switched domain 3GPP has specified a MSC (Mobile Switching 169 Center) server enhanced for ICS (IMS centralized services) and a MSC 170 server enhanced for SR-VCC (Single Radio Voice Call Continuity) that 171 control mobile voice call setup over the circuit switched radio 172 access while establishing the corresponding voice session in the core 173 network using SIP/IMS. To enable this, the MSC server enhanced for 174 ICS or MSC server enhanced for SR-VCC, perform SIP registration on 175 behalf of the mobile device which is also simultaneously directly 176 registered with the IP/SIP/IMS domain. The only mobile device 177 identifier that is transportable using GSM/UMTS/LTE signaling is the 178 IMEI therefore the instance-id included by the MSC server enhanced 179 for ICS or the MSC server enhanced for SR-VCC when acting on behalf 180 of the mobile device, and the instance-id directly included by the 181 mobile device both need to be based on the IMEI. 183 Additionally in order to meet the above requirements, the same IMEI 184 that is obtained from the circuit switched signaling by the MSC 185 server needs to be obtainable from SIP signaling so that that it can 186 be determined that both the SIP signaling and circuit switched 187 signaling originate from the same mobile device. 189 3GPP TS 24.237 [12] and 3GPP TS 24.292 [13] already specify the use 190 of the URN namespace for the GSMA IMEI URN as specified in 191 draft-montemurro-gsma-imei-urn-20 [1] as the instance-id used by GSM/ 192 UMTS/LTE mobile devices, the MSC server enhanced for SR-VCC and the 193 MSC server enhanced for ICS, for SIP/IMS registrations and emergency 194 related SIP requests for these reasons. 196 4. 3GPP Use Cases 198 1. The mobile device includes its IMEI in the SIP REGISTER request 199 so that the SIP registrar can perform a check of the Equipment 200 Identity Register (EIR) to verify if this mobile device is allowed or 201 barred from accessing the network for non-emergency services (e.g., 202 because it has been stolen). If the mobile device is not allowed to 203 access the network for non-emergency services the SIP registrar can 204 reject the registration. Thus a barred mobile device is prevented 205 from accesssing the network for non-emergency services. 207 2. The mobile device includes its IMEI in SIP INVITE requests used 208 to establish emergency sessions. This is so that the PSAP (Public 209 Safety Answering Point) can obtain the IMEI of the mobile device for 210 identification purposes if required by regulations. 212 3. The inclusion by the mobile device of its IMEI in SIP INVITE 213 requests used to establish emergency sessions is also used in the 214 cases of unauthenticated emergency sessions to enable the network to 215 identify the mobile device. This is especially important if the 216 unauthenticated emergency session is handed over from the packet 217 switched domain to the circuit switched domain. In this scenario the 218 IMEI is the only identifier that is common to both domains that the 219 Emergency Access Transfer Function (EATF) in the network, that 220 coordinates the transfer between domains, can use to identify that 221 the circuit switched call is from the same mobile device that was in 222 the emergency session in the packet switched domain. 224 5. User Agent Client Procedures 226 A UAC that has an IMEI as specified in 3GPP TS 23.003 [10] that is 227 registering with a 3GPP IMS network MUST include in the 228 "sip.instance" media feature tag the GSMA IMEI URN according to the 229 syntax specified in draft-montemurro-gsma-imei-urn-20 [1] when 230 performing the registration procedures specified in RFC 5626 [2] or 231 RFC 5627 [3] or any other procedure requiring the inclusion of the 232 "sip.instance" media feature tag. The UAC SHOULD NOT include the 233 optional "svn" parameter in the GSMA IMEI URN in the "sip.instance" 234 media feature tag, since the software version can change as a result 235 of upgrades to the device firmware which would create a new 236 instance-id. Any future non zero values of the "vers" parameter, or 237 the future definition of additional parameters for the GSMA IMEI URN 238 that are intended to be used as part of an instance-id will require 239 an update to be made to this RFC. The UAC MUST provide character-by- 240 character identical URNs in each registration according to RFC 5626 241 [2]. Hence, any optional or variable components of the URN (e.g., 242 the "vers" parameter) MUST be presented with the same values and in 243 the same order in every registration as in the first registration. 245 A UAC MUST NOT use the GSMA IMEI URN as an instance-id except when 246 registering with a 3GPP IMS network. When a UAC is operating in IMS 247 mode it will obtain the domain of the network to register with from 248 the UICC (commonly known as the SIM card). This is a carrier's IMS 249 network domain. The UAC will also obtain the address of the IMS edge 250 proxy to send the REGISTER request containing the IMEI using 251 information elelments in the Attach response when it attepts to 252 connect to the carriers packet data network. When registering with a 253 non-3GPP IMS network a UAC SHOULD use a UUID as an instance-id as 254 specified in RFC 5626 [2]. 256 A UAC MUST NOT include the "sip.instance" media feature tag 257 containing the GSMA IMEI URN in the Contact header field of non- 258 REGISTER requests except when the request is related to an emergency 259 session. Regulatory requirements can require the IMEI to be provided 260 to the Public Safety Answering Point (PSAP). Any future exceptions 261 to this prohibition require a RFC that addresses how privacy is not 262 violated by such a usage. 264 6. User Agent Server Procedures 266 A UAS MUST NOT include its "sip.instance" media feature tag 267 containing the GSMA IMEI URN in the Contact header field of responses 268 except when the response is related to an emergency session. 269 Regulatory requirements can require the IMEI to be provided to the 270 Public Safety Answering Point(PSAP). Any future exceptions to this 271 prohibition require a RFC that addresses how privacy is not violated 272 by such a usage. 274 7. 3GPP SIP Registrar Procedures 276 In 3GPP IMS when the SIP Registrar receives in the Contact header 277 field a "sip.instance" media feature tag containing the GSMA IMEI URN 278 according to the syntax specified in 279 draft-montemurro-gsma-imei-urn-20 [1] the SIP registrar follows the 280 procedures specified in RFC 5626 [2]. The IMEI URN MAY be validated 281 as described in draft-montemurro-gsma-imei-urn-20 [1]. If the UA 282 indicates that it supports the extension in RFC 5627 [3] and the SIP 283 Registrar allocates a public GRUU according to the procedures 284 specified in RFC 5627 [3] the instance-id MUST be obfuscated when 285 creating the "gr" parameter in order not to reveal the IMEI to other 286 UAs when the public GRUU is included in non-REGISTER requests and 287 responses. 3GPP TS 24.229 [8] subclause 5.4.7A.2 specifies the 288 mechanism for obfuscating the IMEI when creating the "gr" parameter. 290 8. IANA considerations 292 This document defines no items requiring action by IANA. 294 9. Security considerations 296 Because IMEIs like other formats of instance-ids can be correlated to 297 a user, they are they are personally identifiable informationneed and 298 MUST be treated as any other personally identifiable information. In 299 particular, the "sip.instance" media feature tag containing the GSMA 300 IMEI URN MUST NOT be included in requests or responses intended to 301 convey any level of anonymity, as this could violate the users 302 privacy. RFC 5626 [2] states "One case where a UA could prefer to 303 omit the "sip.instance" media feature tag is when it is making an 304 anonymous request or some other privacy concern requires that the UA 305 not reveal its identity". The same concerns apply when using the 306 GSMA IMEI URN as an instance-id. Publication of the GSMA IMEI URN to 307 networks that the UA is not attached to or the UA does not have a 308 service relationship with is a security breach and the "sip.instance" 309 media feature tag MUST NOT be forwarded by the service provider's 310 network elements when forwarding requests or responses towards the 311 destination UA. Additionally, an instance-id containing the GSMA 312 IMEI URN identifies a mobile device and not a user. The instance-id 313 containing the GSMA IMEI URN MUST NOT be used alone as an address for 314 a user or as an identification credential for a user. The GRUU 315 mechanism specified in RFC 5627 [3] provides a means to create URIs 316 that address the user at a specific device or User Agent. 318 Entities that log the instance ID need to protect them as personally 319 identifiable information. Regulatory requirements can require 320 carriers to log SIP IMEIs. 322 In order to protect the "sip.instance" media feature tag containing 323 the GSMA IMEI URN from being tampered with, those REGISTER requests 324 containing the GSMA IMEI URN MUST be sent using a security mechanism 325 such as TLS (RFC 4346 [5]) or another security mechanism that 326 provides equivalent levels of protection such as hop-by-hop security 327 based upon IPSec. 329 10. Acknowledgements 331 The author would like to thank Paul Kyzivat, Dale Worley, Cullen 332 Jennings, Adam Roach, Keith Drage, Mary Barnes, Peter Leis, James Yu, 333 S. Moonesamy, Roni Even, and Tim Bray for reviewing this draft and 334 providing their comments. 336 11. References 338 11.1. Normative references 340 [1] Montemurro, M., "A Uniform Resource Name Namespace For The 341 Global System for Mobile communications Association (GSMA) and 342 the International Mobile station Equipment Identity(IMEI), work 343 in progress", Internet Draft draft-montemurro-gsma-imei-urn-20, 344 February 2014. 346 [2] Jennings, C., Mahy, R., and F. Audet, "Managing Client- 347 Initiated Connections in the Session Initiation Protocol 348 (SIP)", RFC 5626, October 2009. 350 [3] Rosenberg, J., "Obtaining and Using Globally Routable User 351 Agent URIs (GRUUs) in the Session Initiation Protocol (SIP)", 352 RFC 5627, October 2009. 354 [4] Moats, R., "URN Syntax", RFC 2141, May 1997. 356 [5] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) 357 Protocol Version 1.1", RFC 4346, April 2006. 359 [6] Leach, P., Mealling, M., and R. Salz, "A Universally Unique 360 IDentifier (UUID) URN Namespace", RFC 4122, July 2005. 362 [7] Bradner, S., "Key words for use in RFCs to Indicate Requirement 363 Levels", BCP 14, RFC 2119, March 1997. 365 [8] 3GPP, "TS 24.229: IP multimedia call control protocol based on 366 Session Initiation Protocol (SIP) and Session Description 367 Protocol (SDP); Stage 3 (Release 8)", 3GPP 24.229, 368 September 2013, 369 . 371 [9] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., 372 Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: 373 Session Initiation Protocol", RFC 3261, June 2002. 375 11.2. Informative references 377 [10] 3GPP, "TS 23.003: Numbering, addressing and identification 378 (Release 8)", 3GPP 23.003, September 2013, 379 . 381 [11] GSMA Association, "IMEI Allocation and Approval Guidelines", 382 PRD TS.06 (DG06) version 6.0, July 2011, . 386 [12] 3GPP, "TS 24.237: Mobile radio interface Layer 3 specification; 387 Core network protocols; Stage 3 (Release 8)", 3GPP 24.237, 388 September 2013, 389 . 391 [13] 3GPP, "TS 24.292: IP Multimedia (IM) Core Network (CN) 392 subsystem Centralized Services (ICS); Stage 3 (Release 8)", 393 3GPP 24.292, June 2013, 394 . 396 Author's Address 398 Andrew Allen (editor) 399 Blackberry 400 1200 Sawgrass Corporate Parkway 401 Sunrise, Florida 33323 402 USA 404 Email: aallen@blackberry.com