4.13 Detach principles

23.4023GPPArchitecture enhancements for non-3GPP accessesRelease 18TS

When a UE is attached to Evolved Packet Core via multiple access systems, the following principles shall apply during the detach procedure:

– A UE that is detaching from the Evolved Packet Core (e.g. a UE that is powering off) shall perform the UE initiated detach procedure on each of the access systems through which the UE is attached to Evolved Packet Core.

– A UE that is detaching from a specific access system and wants to preserve all or a subset of the active PDN connections that use that access system shall initiate UE initiated PDN disconnection procedure for each of the PDN connection which is not required to be preserved. The UE then shall initiate the applicable handover procedure to transfer to the access system through which the UE remains attached to the Evolved Packet Core each of the PDN connections to be preserved.

– When HSS initiates the detach procedure to delete the UE from the Evolved Packet Core (e.g. due to subscription expiry, etc), HSS/AAA initiated detach procedure should be performed towards each node registered for the UE.