Editing My 3GPP 23.501 Notes (section)

==== 5.3.2.1 General ====

A UE/user needs to register with the network to receive services that requires registration. Once registered and if applicable the UE updates its registration with the network (see TS 23.502):
* periodically, in order to remain reachable (Periodic Registration Update); or
* upon mobility (Mobility Registration Update); or
* to update its capabilities or re-negotiate protocol parameters (Mobility Registration Update).

The Initial Registration procedure involves execution of Network Access Control functions as defined in clause 5.2 (i.e. user authentication and access authorization based on subscription profiles in UDM). As result of the Registration procedure, the identifier of the serving AMF serving the UE in the access through which the UE has registered will be registered in UDM.

The registration management procedures are applicable over both 3GPP access and Non-3GPP access. The 3GPP and Non-3GPP RM states are independent of each other, see clause 5.3.2.4.