LTE : In which scenario, UE sends "random number" within the RRC connection request message ?

Question

Usually, I always saw when UE sends "S-TMSI" in RRC connection Request message then it definitely sends "Registered MME Information " in RRC Connection Setup Complete message.

I am looking for a scenario on which UE sends "Random number" in RRC Connection Request message and "Registered MME Information" in RRC Connection Setup Complete message.

Answer 1

As per 24.301...

When the UE is not registered in the tracking area of the current cell during the NAS signalling connection
establishment, the UE NAS does not provide the lower layers with the S-TMSI. If the UE has a valid registered
MME identifier from a previous registration, the UE NAS shall provide the lower layers with the registered
MME identifier.

So in this scenario when ue is making rrc connection with cell having not registed tracking area, UE will send random number in rrc Connection request and registered MME info in rrc Connection complete msg.

Comments

Thanks a lot Veer Pal Singh Yadav for your answer.