UE and devices for detach handling

A non-transitory computer readable medium comprising instructions that, when executed by processing circuitry of an apparatus of a mobility management entity (MME) of a network, the network configured to communicate with user equipment (UE) that are configured to send detach requests without any integrity protection when attached to the network for emergency bearer services with no shared evolved packet system (EPS) security context available, the processing circuitry configured to cause the apparatus to:

• receive, at an interface, a non-access stratum (NAS) message comprising a UE-initiated detach request associated with a first user equipment (UE) in an EMM-REGISTERED state;
• determine whether the detach request is received from the UE without integrity protection;
• analyze one or more additional criteria associated with the detach request in response to confirmation that the detach request message is received from the UE without the integrity protection to determine whether the UE is attached to the network for emergency bearer services with no shared EPS security context available;
• and
• manage an EPS mobility management (EMM) registration state for the first UE based on analysis of the one or more additional criteria,
• wherein the one or more additional criteria includes at least one of whether the UE is performing periodic tracking area updating and whether the UE is responding to paging, and
• wherein to manage the EPS EMM registration state, the processing circuitry is configured to:
• ignore the detach request, the UE is to remain in the EMM-REGISTERED state, when the detach request was received without integrity protection when the UE has performed the periodic tracking area updating since receipt of the detach request or when the UE has responded to paging since receipt of the detach request, and
• process the detach request when the detach request was received without integrity protection when the UE has not performed the periodic tracking area updating since receipt of the detach request or when the UE has not responded to paging since receipt of the detach request,
• wherein the detach request is determined to be fraudulent when the detach request was received without integrity protection when the UE has performed the periodic tracking area updating since receipt of the detach request or when the UE has responded to paging since receipt of the detach request, and
• wherein the detach request is determined to be genuine when the detach request was received without integrity protection when the UE has not performed the periodic tracking area updating since receipt of the detach request or when the UE has not responded to pacing since receipt of the detach request.