RRC Connection Release

Release is allways initiated by Network

Call flow:
Utran to UE : RRC Conn Release (DCCH)
UE to Utran : RRC Conn Release Complete (DCCH)

If dedicated connection exists then both messages will be sent on Un-Acknowledged mode as DCCH is present. As this is un-acknowledged mode, UE may respond several times (based on timer v308 timer)

or

If there is no dedicated connection RRC Conn.Release sent on FACH and RRC Connection Rel.complete will be sent on RACH. This happens on Acknowledged mode so, there will not be repetetion here and only sent once.

*When UE receives RRC Conn.Release message when it is in CELL_FACH state, UE will not send RRC Conn.rel.Complete but UE releases all Radio resources and moved to Idle state