Dispatch Working Group A. Allen, Ed.
Internet-Draft Research in Motion (RIM)
Intended status: Informational October 13, 2010
Expires: April 16, 2011
Using the International Mobile station Equipment Identity(IMEI)URN as an
Instance ID
draft-allen-dispatch-imei-urn-as-instanceid-00
Abstract
This specification defines how the Uniform Resource Name namespace
reserved for GSMA identities and its sub namespace for the IMEI
(International Mobile station Equipment Identity) can be used as an
instance-id as specified in RFC 5626 [1] and also as used by RFC 5627
[2].
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. User Agent Client Procedures . . . . . . . . . . . . . . . . . 5
5. Registrar Procedures . . . . . . . . . . . . . . . . . . . . . 5
6. Security considerations . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative references . . . . . . . . . . . . . . . . . . . 6
8.2. Informative references . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
This specification defines how the Uniform Resource Name namespace
reserved for GSMA identities and its sub namespace for the IMEI
(International Mobile station Equipment Identity) as defined in
draft-montemurro-gsma-imei-urn-05 [3] can be used as an instance-id
as specified in RFC 5626 [1] and also as used by RFC 5627 [2].
RFC 5626 [1] defines the "+sip.instance" Contact header field
parameter which contains a URN as per RFC 2141 [4] defined as an
instance-id that uniquely identifies a specific UA instance. This
instance-id is used as defined in RFC 5626 [1] so that registrar can
recognize that the contacts from multiple registrations correspond to
the same UA. The instance-ID is also used as defined by RFC 5627 [2]
to create Globally Routable User Agent URIs (GRUUs) that can be used
to uniquely address a UA when multiple UAs are registered with the
same Address of Record (AoR).
RFC 5626 [1] defines that a UA SHOULD create a Universally Unique
Identifier (UUID) URN as defined in RFC 4122 [6] as its instance-id
but allows for the possibility of other URN schemes to be used. If a
URN scheme other than UUID is used, the UA MUST only use URNs for
which an RFC (from the IETF stream) defines how the specific URN
needs to be constructed and used in the "+sip.instance" Contact
header field parameter for outbound behavior. This specification
meets this requirement by specifying how the GSMA IEMEI URN is used
in the "+sip.instance" Contact header field parameter for outbound
behavior and draft-montemurro-gsma-imei-urn-05 [3] defines how the
GSMA IMEI URN is constructed
The GSMA IMEI is an identifier for a namespace for the IMEI a
globally unique identifier that identifies Mobile Equipment used in
Global System for Mobile (GSM), Universal Mobile Telecommunications
System (UMTS) and 3GPP LTE (Long Term Evolution)networks. The IMEI
allocation is managed by the GSMA to ensure that the IMEI values are
globally unique. Details of the formatting of the IMEI as a URN are
defined in draft-montemurro-gsma-imei-urn-05 [3] and the definition
of the IMEI is contained in 3GPP TS 23.003 [7]. Further details
about the GSMA role in allocating the IMEI and the IMEI allocation
guidelines can be found in GSMA PRD DG.06 [8]
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [5].
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3. Background
GSM and UMTS capable mobile devices represent 90% of the mobile
devices in use worldwide. GSM and UMTS mobile devices each have a
unique IMEI allocated which uniquely identifies the mobile device
from all other GSM/UMTS mobile devices deployed. Amongst other
things in some regulatory jurisdictions the IMEI is used to identify
a stolen mobile is being used and help to identify the subscription
that is using it and to prevent its use. Whilst GSM was originally a
circuit switched system enhancements such as GPRS (General Packet
Radio Service) and UMTS have added IP data capabilities which along
with the definition of the IP Multimedia Subsystem (IMS) has made SIP
based calls and IP multimedia sessions from mobile devices possible.
The latest enhancment known as LTE will introduce even higher data
rates and dispenses with the circuit switched domain completely
meaning that with LTE voice calls will need to be conducted using IP
and IMS. However, the transition to all IP, SIP based IMS networks
worldwide will take a great many years and mobile devices being
mobile will need to operate in both IP/SIP/IMS mode and circuit
switched mode. In fact calls and sessions will need to be handed
over between IP/SIP/IMS mode and circuit switched mode during a call.
Also as many existing GSM and UMTS radio access networks are unable
to support IP/SIP/IMS based voice services in a commercially
acceptable manner some sessions may have some media types delivered
via IP/IMS simultaneously with voice media delivered via circuit
switched with the same mobile device simultaneously attached via both
the IP/SIP/IMS domain and the circuit switched domain. To meet this
need 3GPP has specified how to maintain session continuity between
the IP/SIP/IMS domain and the circuit switched domain in 3GPP TS
24.237 [9] and how to access IMS hosted services via both the IP/SIP/
IMS domain and the circuit switched domain in 3GPP TS 24.292 [10].
In order for the the mobile device to access SIP/IMS services via the
circuit switched domain 3GPP has defined a MSC (Mobile switching
Center) server enhanced for ICS which controls mobile voice call
setup over the circuit switched radio access while establishing the
corresponding voice session in the core network using SIP/IMS. To
enable this the MSC server enhanced for ICS (IMS centralized
services) performs SIP registration on behalf of the mobile device
which may simultaneously also be directly registered with the IP/SIP/
IMS domain. The SIP/IMS network needs to be able to identify that
both of these SIP registrations are from the same UA instance and
also correctly handle sessions establishment requests addressed using
GRUUs as defined in RFC 5627 [2] when the mobile device is attached
using the circuit switched domain. The only mobile device identifier
that is transportable using GSM/UMTS/LTE signaling is the IMEI
therefore the instance-id used by the MSC server enhanced for ICS
when registering on behalf of the mobile device and the instance-id
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when the mobile device registers directly needs to be based on the
IMEI.
Additionally in order to meet the regulatory requirements to use the
IMEI to identify a stolen mobile is being used and help to identify
the subscription that is using it and to prevent its use the same
IMEI that is obtained from the circuit switched signaling needs to be
obtainable from SIP signaling.
3GPP TS 24.237 [9] and 3GPP TS 24.292 [10] already define the use of
the URN namespace for the GSMA and IMEI as defined in
draft-montemurro-gsma-imei-urn-05 [3] as the instance-id used by
mobile devices and the MSC server enhanced for ICS for SIP/IMS
registrations for these reasons.
4. User Agent Client Procedures
A UAC that has an IMEI as defined in 3GPP TS 23.003 [7] SHALL include
in the "sip.instance" media feature tag the GSMA IMEI URN according
to the syntax defined in draft-montemurro-gsma-imei-urn-05 [3] when
performing the registration procedures defined in RFC 5626 [1] or RFC
5627 [2] or any other procedure requiring including the
"sip.instance" media feature tag. The UA SHOULD NOT include the
"sip.instance" media feature tag in non REGISTER requests.
5. Registrar Procedures
A Registrar that receives in the Contact header field a
"sip.instance" media feature tag containing the GSMA IMEI URN
according to the syntax defined in draft-montemurro-gsma-imei-urn-05
[3] SHOULD follow the procedures defined in RFC 5626 [1] and RFC 5627
[2] if those extensions are supported and indicated as supported by
the UA. If the URN in the "sip.instance" media feature tag contains
any parameters (such as the "svn" or "vers" parameters) these are
ignored when comparing the instance-id from multiple registrations to
determine whether two instance-id are for the same UA. A Registrar
that allocates a GRUU according to the procedures defined in RFC 5627
[2] SHOULD obfuscate the instance-id when creating the "gr" parameter
in order not to reveal the IMEI to other UAs when the GRUU is
included in non register requests. 3GPP TS 24.229 [11] defines a
suitable mechanism for obfuscating the IMEI when creating the "gr"
parameter.
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6. Security considerations
The "sip.instance" media feature tag containing the GSMA IMEI URN
SHOULD not be sent in non REGISTER requests which can pass end to end
as this would allow 3rd parties to obtain IMEIs and potentially allow
spoofing of mobile devices. In order to protect the IMEIs register
requests containing the GSMA IMEI URN SHOULD be sent using a security
mechanism such as TLS [12] (or other security mechanism that provides
equivalent levels of protection) to protect the IMEI from being
intercepted.
When used to generate a GRUU the registrar SHOULD obfuscate the
instance-id when creating the "gr" parameter in order not to reveal
the IMEI to other UAs when the GRUU is included in non register
requests. 3GPP TS 24.229 [11] defines a suitable mechanism for
obfuscating the IMEI when creating the "gr" parameter.
7. Acknowledgements
NEED TO FILL THIS OUT
8. References
8.1. Normative references
[1] Jennings, C., Mahy, R., and F. Audet, "Managing Client-
Initiated Connections in the Session Initiation Protocol
(SIP)", RFC 5626, October 2009.
[2] Rosenberg, J., "Obtaining and Using Globally Routable User
Agent URIs (GRUUs) in the Session Initiation Protocol (SIP)",
RFC 5627, October 2009.
[3] Montemurro, M., "A Uniform Resource Name Namespace For The GSM
Association (GSMA) and the International Mobile station
Equipment Identity(IMEI), work in progress", Internet
Draft draft-montemurro-gsma-imei-urn-05, September 2010.
[4] Moats, R., "URN Syntax", RFC 2141, May 1997.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
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8.2. Informative references
[6] Leach, P., Mealling, M., and R. Salz, "A Universally Unique
IDentifier (UUID) URN Namespace", RFC 4122, July 2005.
[7] 3GPP, "TS 23.003: Numbering, addressing and identification
(Release 8)", 3GPP 23.003, September 2008,
<ftp://ftp.3gpp.org/Specs/archive/23_series/23.003/>.
[8] GSMA Association, "IMEI Allocation and Approval Guidelines",
PRD DG.06 version 3.6, February 2008,
<http://gsmworld.com/newsroom/document%2Dlibrary/>.
[9] 3GPP, "TS 24.237: Mobile radio interface Layer 3 specification;
Core network protocols; Stage 3 (Release 8)", 3GPP 24.237,
March 2009,
<ftp://ftp.3gpp.org/Specs/archive/24_series/24.237/>.
[10] 3GPP, "TS 24.292: IP Multimedia (IM) Core Network (CN)
subsystem Centralized Services (ICS); Stage 3 (Release 8)",
3GPP 24.292, March 2009,
<ftp://ftp.3gpp.org/Specs/archive/24_series/24.292/>.
[11] 3GPP, "TS 24.229: IP multimedia call control protocol based on
Session Initiation Protocol (SIP) and Session Description
Protocol (SDP); Stage 3 (Release 8)", 3GPP 24.229, March 2009,
<ftp://ftp.3gpp.org/Specs/archive/24_series/24.229/>.
[12] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999.
Author's Address
Andrew Allen (editor)
Research in Motion (RIM)
2550 West Golf Road
Rolling Meadows, Illinois 60008
USA
Phone: unlisted
Fax: unlisted
Email: aallen@rim.com
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