Section: 13.4B Temporary Public User Identity
Content: For 3GPP systems, if there is no ISIM application to host the Public User Identity, a Temporary Public User Identity shall be derived, based on the IMSI. The Temporary Public User Identity shall be of the form as described in clause 13.4 and shall consist of the string "sip:" appended with a username and domain portion equal to the IMSI derived Private User Identity, as described in clause 13.2. An example using the same example IMSI from clause 13.2 can be found below: EXAMPLE: "sip:234150999999999@ims.mnc015.mcc234.3gppnetwork.org". The temporary public user identity for a Stand-alone Non-Public Network (SNPN) subscriber with an IMSI-based SUPI type, shall use the IMSI-based derivation described above, and append nid<NID> of the SNPN, in between the "ims." and "mnc<MNC>" labels. NOTE: The UE takes the NID from "list of subscriber data" as specified in 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [139], from the entry selected by the UE. EXAMPLE for an SNPN: "sip:234150999999999@ims.nid000007ed9d5.mnc015.mcc234.3gppnetwork.org". The temporary Public User Identity for a Stand-alone Non-Public Network (SNPN) subscriber identified by a SUPI containing a network-specific identifier that takes the form of an NAI consists of the string "sip:" appended with a username and realm portion equal to the NAI SUPI derived Private User Identity. For 3GPP2 systems, if there is no IMC present, the UE shall derive the public user identity as described in Annex C of 3GPP2 X.S0013-004 [67].