Hi Core network guys.
If TAU request fails, during 10 seconds before UE initiate 2nd TAU request, is the UE allowed to initiate calls or answer to pagings?
As far as I know without a TAU accept UE is not allowed to do anything.
Anyone could please point me to right 3gpp spec for this?
Or at least let me know what the UE right behaviour should be for this NAS case.
IMO, UE can’t answer to paging on that cell.
For that matter, UE directed paging is not expected from MME without forming a context in that MME.
What is the reason for TAU failure?
Is it due to MSG1 failure or RACH accepted but no response from MME?
Closest answer I can find is this from 3GPP TS 24.301 V16.8.0:
(From your scenario, I understand UE is registered with network and moved to new cell which is not in its TAI list.)
5.2.3 UE behaviour in state EMM-REGISTERED
5.2.3.2 Detailed description of UE behaviour in state EMM-REGISTERED
5.2.3.2.7 ATTEMPTING-TO-UPDATE-MM
The UE:
- shall perform cell selection/reselection according to 3GPP TS 36.304 [21];
- shall be able to receive and transmit user data and signalling information;
- shall initiate combined tracking area updating procedure indicating “combined TA/LA updating with IMSI attach” on the expiry of timers T3411 or T3402 or when the UE enters a tracking area not in the list of registered tracking areas and not in one of the lists of forbidden tracking areas;
- shall respond to paging with IMSI or S-TMSI for the PS domain;
