Content for  TS 23.402  Word version:  18.3.0

In order to access the 3GPP Evolved Packet Core from non-3GPP accesses, and get Authentication, Authorization and Accounting services from the Evolved Packet Core, the NAI RFC 4282 based user identification defined in TS 23.003 shall be used. In order to support network-based and client-based mobility related services from the evolved packet core, the NAI RFC 4282 based user identification as defined in TS 23.003 shall be used by the network and mobility clients. The username part of NAI shall be based on IMSI. For emergency attached UEs to the HRPD access which do not have authenticated IMSI, the username part of the MN NAI shall be based on IMEI as defined in TS 23.003 for S2a and S101 reference points (see clause 9). IMSI shall be used for user identification on the GTP based S2b interface. For emergency services over WLAN, an UE that has an IMSI shall contruct the NAI with the username part based on IMSI. If the UE does not have an IMSI, it shall construct the NAI with the username part based on IMEI. For emergency attached UEs to the WLAN access which do not have authenticated IMSI (including the case authentication was not performed), IMEI shall be used for user identification for Authorization and Accounting services from the Evolved Packet Core, as well as on the GTP based S2b interface. User identification in non-3GPP accesses may require additional identities that are out of the scope of 3GPP. These user identities, if not compliant to TS 23.003, are however not sufficient to identify a user in the 3GPP Evolved Packet Core.

With GTP based S2b an EPS Bearer ID uniquely identifies an S2b bearer between an ePDG and a PDN-GW for one UE accessing via non 3GPP access (see clause 4.10.3). This EPS Bearer ID is allocated by the ePDG and is not known to the UE. With GTP based S2a an EPS Bearer ID uniquely identifies an S2a bearer between a TWAN and a PDN-GW for one UE accessing via trusted WLAN access. This EPS Bearer ID is allocated by the TWAN and is not known to the UE. The EPS Bearer IDs assigned for a specific UE on S2b are independent of the EPS Bearer IDs assigned for the same UE on S5/S8 and may overlap in value. The EPS Bearer IDs assigned for a specific UE on S2a are independent of the EPS Bearer IDs assigned for the same UE on S5/S8 and may overlap in value.