EPC: S1 release (not implemented)
The S1 release procedure for user inactivity is currently a not implmeneted feature.
When a UE is idle for a certain period of time (usually 10-30 seconds in commercial networks), after the RRC inactivity timer times out, the eNodeB will send a UE Context Release Request with cause #20 (closed) (user inactivity) to the EPC.
user inactivity is the most common cause for S1 release, but it can happen due to:
- repeated RRC signaling integrity check failure
- release due to UE generated signaling connection release
- unspecified failure
- O&M intervention
- authentication failure
- disallowed CSG cell
More detailed information of S1 release procedure can be found here: