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Mobile stati...' -- The document date (July 6, 2013) is 3940 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-20) exists of draft-montemurro-gsma-imei-urn-15 ** Obsolete normative reference: RFC 2141 (ref. '4') (Obsoleted by RFC 8141) -- Obsolete informational reference (is this intentional?): RFC 4346 (ref. '12') (Obsoleted by RFC 5246) Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). 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 July 6, 2013 5 Expires: January 7, 2014 7 Using the International Mobile station Equipment Identity(IMEI)URN as an 8 Instance ID 9 draft-allen-dispatch-imei-urn-as-instanceid-10 11 Abstract 13 This specification defines how the Uniform Resource Name namespace 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 as specified in RFC 5626 [1] 17 and also as used by RFC 5627 [2]. Its purpose is to fulfil the 18 requirements in RFC 5626 [1] that state "If a URN scheme other than 19 UUID is used, the UA MUST only use URNs for which an RFC (from the 20 IETF stream) defines how the specific URN needs to be constructed and 21 used in the "+sip.instance" Contact header field parameter for 22 outbound behavior." 24 Status of this Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on January 7, 2014. 41 Copyright Notice 43 Copyright (c) 2013 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 4. 3GPP Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 5 66 5. User Agent Client Procedures . . . . . . . . . . . . . . . . . 5 68 6. User Agent Server Procedures . . . . . . . . . . . . . . . . . 6 70 7. 3GPP Registrar Procedures . . . . . . . . . . . . . . . . . . . 6 72 8. IANA considerations . . . . . . . . . . . . . . . . . . . . . . 7 74 9. Security considerations . . . . . . . . . . . . . . . . . . . . 7 76 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 78 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 79 11.1. Normative references . . . . . . . . . . . . . . . . . . . 8 80 11.2. Informative references . . . . . . . . . . . . . . . . . . 8 82 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9 84 1. Introduction 86 This specification defines how the Uniform Resource Name namespace 87 reserved for GSMA identities and its sub namespace for the IMEI 88 (International Mobile station Equipment Identity) as defined in 89 draft-montemurro-gsma-imei-urn-15 [3] can be used as an instance-id 90 as specified in RFC 5626 [1] and also as used by RFC 5627 [2]. 92 RFC 5626 [1] defines the "+sip.instance" Contact header field 93 parameter which contains a URN as per RFC 2141 [4] defined as an 94 instance-id that uniquely identifies a specific UA instance. This 95 instance-id is used as defined in RFC 5626 [1] so that registrar can 96 recognize that the contacts from multiple registrations correspond to 97 the same UA. The instance-id is also used as defined by RFC 5627 [2] 98 to create Globally Routable User Agent URIs (GRUUs) that can be used 99 to uniquely address a UA when multiple UAs are registered with the 100 same Address of Record (AoR). 102 RFC 5626 [1] defines that a UA SHOULD create a Universally Unique 103 Identifier (UUID) URN as defined in RFC 4122 [7] as its instance-id 104 but allows for the possibility of other URN schemes to be used. "If 105 a URN scheme other than UUID is used, the UA MUST only use URNs for 106 which an RFC (from the IETF stream) defines how the specific URN 107 needs to be constructed and used in the "+sip.instance" Contact 108 header field parameter for outbound behavior." This specification 109 meets this requirement by specifying how the GSMA IMEI URN is used in 110 the "+sip.instance" Contact header field parameter for outbound 111 behavior and draft-montemurro-gsma-imei-urn-15 [3] defines how the 112 GSMA IMEI URN is constructed. 114 The GSMA IMEI URN is a namespace for the IMEI a globally unique 115 identifier that identifies mobile devices used in the Global System 116 for Mobile communications(GSM), Universal Mobile Telecommunications 117 System (UMTS) and 3GPP LTE (Long Term Evolution)networks. The IMEI 118 allocation is managed by the GSMA to ensure that the IMEI values are 119 globally unique. Details of the formatting of the IMEI as a URN are 120 defined in draft-montemurro-gsma-imei-urn-15 [3] and the definition 121 of the IMEI is contained in 3GPP TS 23.003 [8]. Further details 122 about the GSMA role in allocating the IMEI and the IMEI allocation 123 guidelines can be found in GSMA PRD TS.06 [9]. 125 2. Terminology 127 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 128 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 129 document are to be interpreted as described in [5]. 131 3. Background 133 GSM, UMTS and LTE capable mobile devices represent 90% of the mobile 134 devices in use worldwide. Every manufactured GSM, UMTS or LTE mobile 135 device has an allocated IMEI which uniquely identifies this specific 136 mobile device. Amongst other things in some regulatory jurisdictions 137 the IMEI is used to identify that a stolen mobile is being used to 138 help to identify the subscription that is using it and to prevent its 139 use. Whilst GSM was originally a circuit switched system, 140 enhancements such as GPRS (General Packet Radio Service) and UMTS 141 have added IP data capabilities which along with the definition of 142 the IP Multimedia Subsystem (IMS) have made SIP based calls and IP 143 multimedia sessions from mobile devices possible. The latest 144 enhancement known as LTE will introduce even higher data rates and 145 dispenses with the circuit switched infrastructure completely meaning 146 that with LTE voice calls will need to be conducted using IP and IMS. 147 However, the transition to all IP, SIP based IMS networks worldwide 148 will take a great many years and mobile devices being mobile will 149 need to operate in both IP/SIP/IMS mode and circuit switched mode. 150 In fact calls and sessions will need to be handed over between IP/ 151 SIP/IMS mode and circuit switched mode during a call. Also as many 152 existing GSM and UMTS radio access networks are unable to support IP/ 153 SIP/IMS based voice services in a commercially acceptable manner some 154 sessions can have some media types delivered via IP/IMS 155 simultaneously with voice media delivered via the circuit switched 156 domain with the same mobile device simultaneously attached via both 157 the IP/SIP/IMS domain and the circuit switched domain. To meet this 158 need 3GPP has specified how to maintain session continuity between 159 the IP/SIP/IMS domain and the circuit switched domain in 3GPP TS 160 24.237 [10] and how to access IMS hosted services via both the IP/ 161 SIP/IMS domain and the circuit switched domain in 3GPP TS 24.292 162 [11]. 164 In order for the mobile device to access SIP/IMS services via the 165 circuit switched domain 3GPP has defined a MSC (Mobile Switching 166 Center) server enhanced for ICS (IMS centralized services) and a MSC 167 server enhanced for SR-VCC (Single Radio Voice Call Continuity) which 168 control mobile voice call setup over the circuit switched radio 169 access while establishing the corresponding voice session in the core 170 network using SIP/IMS. To enable this, the MSC server enhanced for 171 ICS or MSC server enhanced for SR-VCC perform SIP registration on 172 behalf of the mobile device which can also be simultaneously directly 173 registered with the IP/SIP/IMS domain. The only mobile device 174 identifier that is transportable using GSM/UMTS/LTE signaling is the 175 IMEI therefore the instance-id included by the MSC server enhanced 176 for ICS or the MSC server enhanced for SR-VCC when acting on behalf 177 of the mobile device and the instance-id included by the mobile 178 device directly both need to be based on the IMEI. 180 Additionally in order to meet the above requirements, the same IMEI 181 that is obtained from the circuit switched signaling by the MSC 182 server needs to be obtainable from SIP signaling so that that it can 183 be determined that both the SIP signaling and circuit switched 184 signaling originate from the same mobile device. 186 3GPP TS 24.237 [10] and 3GPP TS 24.292 [11] already define the use of 187 the URN namespace for the GSMA IMEI URN as defined in 188 draft-montemurro-gsma-imei-urn-15 [3] as the instance-id used by GSM/ 189 UMTS/LTE mobile devices, the MSC server enhanced for SR-VCC and the 190 MSC server enhanced for ICS for SIP/IMS registrations and emergency 191 related SIP requests for these reasons. 193 4. 3GPP Use Cases 195 1. The mobile device includes its IMEI in the SIP REGISTER request 196 so that the registrar can perform a check of the Equipment Identity 197 Register (EIR) to verify if this mobile device is allowed or barred 198 from accessing the network for non-emergency services (e.g., because 199 it has been stolen). If the mobile device is not allowed to access 200 the network for non-emergency services the registrar can reject the 201 registration. Thus a barred mobile device is prevented from 202 accesssing the network for non-emergency services. 204 2. The mobile device includes its IMEI in SIP INVITE requests used 205 to establish emergency sessions. This is so that the PSAP (Public 206 Safety Answering Point) can obtain the IMEI of the mobile device for 207 identification purposes if required by regulations. 209 3. The inclusion by the mobile device of its IMEI in SIP INVITE 210 requests used to establish emergency sessions is also used in the 211 cases of unauthenticated emergency sessions to enable the network to 212 identify the mobile device. This is especially important if the 213 unauthenticated emergency session is handed over from the packet 214 switched domain to circuit switched domain as in this scenario the 215 IMEI is the only common means for identifying the circuit switched 216 call is from the same mobile device that was in the emergency session 217 in the packet switched domain. 219 5. User Agent Client Procedures 221 A UAC that has an IMEI as defined in 3GPP TS 23.003 [8] that is 222 registering with a 3GPP IMS network MUST include in the 223 "sip.instance" media feature tag the GSMA IMEI URN according to the 224 syntax defined in draft-montemurro-gsma-imei-urn-15 [3] when 225 performing the registration procedures defined in RFC 5626 [1] or RFC 226 5627 [2] or any other procedure requiring the inclusion of the 227 "sip.instance" media feature tag. The UAC SHOULD NOT include the 228 optional "svn" parameter in the GSMA IMEI URN in the "sip.instance" 229 media feature tag, since the software version can change as a result 230 of upgrades to the device firmware which would create a new 231 instance-id. Any future value of the "vers" parameter other than 232 equal to 0 or the future definition of additional parameters for the 233 GSMA IMEI URN that are intended to be used as part of an instance-id 234 will require an update to be made to this RFC. The UAC MUST provide 235 lexically equivalent URNs in each registration [1]. Hence, any 236 optional or variable components of the URN (e.g., the "vers" 237 parameter) MUST be presented with the same values and in the same 238 order in every registration as in the first registration. 240 A UAC MUST only use the GSMA IMEI URN as an instance-id when 241 registering with a 3GPP IMS network. When registering with a non- 242 3GPP IMS network a UAC SHOULD use a UUID as an instance-id as defined 243 in RFC 5626 [1]. 245 A UAC MUST NOT include the "sip.instance" media feature tag 246 containing the GSMA IMEI URN in the Contact header field of non- 247 REGISTER requests except when the request is related to an emergency 248 session. Regulatory requirements can require the IMEI to be provided 249 to the Public Safety Answering Point (PSAP). Any future exceptions 250 to this prohibition require a RFC that addresses how privacy is not 251 violated by such a usage. 253 6. User Agent Server Procedures 255 A UAS MUST NOT include its "sip.instance" media feature tag 256 containing the GSMA IMEI URN in the Contact header field of responses 257 except when the response is related to an emergency session. 258 Regulatory requirements can require the IMEI to be provided to the 259 Public Safety Answering Point(PSAP). Any future exceptions to this 260 prohibition require a RFC that addresses how privacy is not violated 261 by such a usage. 263 7. 3GPP Registrar Procedures 265 In 3GPP IMS when the Registrar receives in the Contact header field a 266 "sip.instance" media feature tag containing the GSMA IMEI URN 267 according to the syntax defined in draft-montemurro-gsma-imei-urn-15 269 [3] the registrar follows the procedures defined in RFC 5626 [1]. If 270 the UA indicates that it supports the extension in RFC 5627 [2] and 271 the Registrar allocates a public GRUU according to the procedures 272 defined in RFC 5627 [2] the instance-id MUST be obfuscated when 273 creating the "gr" parameter in order not to reveal the IMEI to other 274 UAs when the public GRUU is included in non-REGISTER requests and 275 responses. 3GPP TS 24.229 [6] subclause 5.4.7A.2 defines the 276 mechanism for obfuscating the IMEI when creating the "gr" parameter. 278 8. IANA considerations 280 This document defines no items requiring action by IANA. 282 9. Security considerations 284 Because IMEIs like other formats of instance-ids can be loosely 285 correlated to a user, they need to be treated as any other personally 286 identifiable information. In particular, the "sip.instance" media 287 feature tag containing the GSMA IMEI URN MUST NOT be included in 288 requests or responses intended to convey any level of anonymity. RFC 289 5626 [1] states "One case where a UA could prefer to omit the 290 "sip.instance" media feature tag is when it is making an anonymous 291 request or some other privacy concern requires that the UA not reveal 292 its identity". The same concerns apply when using the GSMA IMEI URN 293 as an instance-id. Publication of the GSMA IMEI URN to networks that 294 the UA is not attached to or the UA does not have a service 295 relationship with is a security breach and the "sip.instance" media 296 feature tag MUST NOT be forwarded by the service provider's network 297 elements when forwarding requests or responses towards the 298 destination UA. 300 In order to protect the "sip.instance" media feature tag containing 301 the GSMA IMEI URN from being tampered with, those REGISTER requests 302 containing the GSMA IMEI URN MUST be sent using a security mechanism 303 such as TLS [12] (or another security mechanism that provides 304 equivalent levels of protection). 306 10. Acknowledgements 308 The author would like to thank Paul Kyzivat, Dale Worley, Cullen 309 Jennings, Adam Roach, Keith Drage, Mary Barnes, Peter Leis and James 310 Yu for reviewing this draft and providing their comments. 312 11. References 313 11.1. Normative references 315 [1] Jennings, C., Mahy, R., and F. Audet, "Managing Client- 316 Initiated Connections in the Session Initiation Protocol 317 (SIP)", RFC 5626, October 2009. 319 [2] Rosenberg, J., "Obtaining and Using Globally Routable User 320 Agent URIs (GRUUs) in the Session Initiation Protocol (SIP)", 321 RFC 5627, October 2009. 323 [3] Montemurro, M., "A Uniform Resource Name Namespace For The GSM 324 Association (GSMA) and the International Mobile station 325 Equipment Identity(IMEI), work in progress", Internet 326 Draft draft-montemurro-gsma-imei-urn-15, July 2013. 328 [4] Moats, R., "URN Syntax", RFC 2141, May 1997. 330 [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement 331 Levels", BCP 14, RFC 2119, March 1997. 333 [6] 3GPP, "TS 24.229: IP multimedia call control protocol based on 334 Session Initiation Protocol (SIP) and Session Description 335 Protocol (SDP); Stage 3 (Release 8)", 3GPP 24.229, June 2013, 336 . 338 11.2. Informative references 340 [7] Leach, P., Mealling, M., and R. Salz, "A Universally Unique 341 IDentifier (UUID) URN Namespace", RFC 4122, July 2005. 343 [8] 3GPP, "TS 23.003: Numbering, addressing and identification 344 (Release 8)", 3GPP 23.003, December 2012, 345 . 347 [9] GSMA Association, "IMEI Allocation and Approval Guidelines", 348 PRD TS.06 (DG06) version 6.0, July 2011, . 352 [10] 3GPP, "TS 24.237: Mobile radio interface Layer 3 specification; 353 Core network protocols; Stage 3 (Release 8)", 3GPP 24.237, 354 June 2013, 355 . 357 [11] 3GPP, "TS 24.292: IP Multimedia (IM) Core Network (CN) 358 subsystem Centralized Services (ICS); Stage 3 (Release 8)", 359 3GPP 24.292, June 2013, 360 . 362 [12] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) 363 Protocol Version 1.1", RFC 4346, April 2006. 365 Author's Address 367 Andrew Allen (editor) 368 Blackberry 369 1200 Sawgrass Corporate Parkway 370 Sunrise, Florida 33323 371 USA 373 Phone: unlisted 374 Fax: unlisted 375 Email: aallen@blackberry.com