Section: 13.13 IMEI based identity
Content: The IMEI based identity shall take the form of a SIP URI (see IETF RFC 3261 [26]). The IMEI based identity is included in P-Preferred-Identity header field of SIP INVITE request by the UE and used in cases of unauthenticated emergency sessions as specified in clause 5.1.6.8.2 of 3GPP TS 24.229[ IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ]  [81]. A SIP URI for an IMEI based identity shall take the form "sip:user@domain" where by the user part shall contain the IMEI. The IMEI shall be encoded according to ABNF of imeival as defined in IETF RFC 7254 [79]. The domain part shall contain the home network domain named derived as specified in clause 13.2. An example for the case when the UE has a home network domain name of operator.com is: EXAMPLE 1: "sip:90420156-025763-0@operator.com" An example for 3GPP systems, when the UE with no ISIM application has a home network domain name of ims.mnc015.mcc234.3gppnetwork.org derived from the same example IMSI from clause 13.2 is: EXAMPLE 2: "sip:90420156-025763-0@ims.mnc015.mcc234.3gppnetwork.org"