Section: 6.8.1.1.2.4 UE registration over a second access type to the same AMF
Content: It is assumed in this clause that the UE is already registered over a first access type (say access A). Clauses 6.8.1.1.2.1 and 6.8.1.1.2.2 applies as well when the UE attempts to register over a new access type (access B) to the same AMF with the following addition/exception: Whenever the UE registers over a second access type (access B) to the same AMF, with the intention to transitioning from RM-DEREGISTERED to RM-REGISTERED state, then a full native 5G NAS security context is already available in the UE and the AMF. In this case, the UE shall directly take into use the available full 5G NAS security context and use it to protect the Registration Request over the second access using the distinct pair of NAS COUNTs for this second access type (access B). The AMF may decide to run a new primary authentication as part of the Registration procedure on this second access (access B). If a new primary authentication is run, then the new derived partial 5G NAS security context needs to be taken into use on this second access (access B) with a NAS SMC using the distinct pair of NAS COUNTs for this second access. As the UE is already registered on the first access (access A), then the AMF needs to run a NAS SMC procedure on the first access in order to take the partial 5G NAS security context into use as described in clause 6.4.2.2. If there is a need for the AMF to take a new partial 5G NAS security context into use, derived from primary authentication executed on the first access (access A), then the AMF needs to send a NAS SMC to the UE on the second access (access B) in order to take the new partial 5G NAS security context into use as described in clause 6.4.2.2.