The purpose of the 5G-GUTI is to provide an unambiguous identification of the UE that does not reveal the UE or the
user's permanent identity in the 5G System (5GS). It also allows the identification of the Access and Mobility
Management Function (AMF) and network. It can be used by the network and the UE to establish the UE's identity
during signalling between them in the 5GS.
The 5G-S-TMSI is the shortened form of the 5G-GUTI to enable more efficient radio signalling procedures (e.g. paging
and Service Request). For paging purposes, the mobile is paged with the 5G-S-TMSI. The 5G-S-TMSI shall be
constructed from the AMF Set ID, the AMF Pointer and the 5G-TMSI: