What would be message sequence in LTE network when UE is switched off and switched on later?

Question

In which cases/scenarios, an UE would maintain multiple active NAS connection with the different serving networks ?

Answer 1

When powered OFF, UE will send Detach request. Below image shows example of Detach - UE initiated

Data and signalling Bearers will be released on core side and AS side

Once switched ON, it will follow normal attach procedure by sending Attach request

Detailed message flow and contents can be found here for detach procedure
http://www.netmanias.com/en/post/techdocs/6108/detach-emm-lte/emm-procedure-2-detach