Cellular Network Infrastructure » Core Network (CN) » OsmoMSC

A particular problem is determining which BSSMAP Clear Command cause code indicates a perfectly normal clear after all transactions are done.
RR defines a GSM48_RR_CAUSE_NORMAL, but BSSMAP doesn't define such a "normal" cause.
In 3GPP TS 48.008 the chapter for this situation does not indicate any cause code that should be used (3.1.9.1 "Release Due To Transaction Completion").

3.2.1.21 CLEAR COMMAND says:

Typical Cause values are:
- call control;
- O and M intervention;
- equipment failure;
- requested terrestrial resource unavailable;
- handover successful;
- protocol error between BSS and MSC.

"call control" is mentioned in relation to uplink release and to the BSS requesting a clear.
"O and M intervention" is for Operation and Maintenance, does not apply.
"handover successful" is about handover.
All others are error codes and don't qualify for a normal release.

My conclusion is that "call control" is the normal cause code to send for a Clear Command, even if the transactions were not related to voice calls.