Pix,
The drive test was performed using a 90sec. call, and after that, a redial (almost 100 Call Setups sequences).
This problem was found on 26% of the Call Setups, in different cells, but the same LA.
In that cases, the handshiking was as follows:
UL Channel Request
DL Immediate Assignment
UL SABM-CMD
DL Ciphering Mode Command
UL Ciphering Mode Complete
UL Setup
DL Identity Request
UL Identity Response
DL Call Proceeding
DL Assignment Command
UL Assignment Complete
UL SABM-CMD
DL Disconnect (20 sec. after Ch. Req.)
UL Release (Call End – NW Initiated Release)
DL Release Complete
DL Channel Release
UL DISC-CMD
DL UA-RSP
So, there is an Assignment Complete msg, but there’s no Alerting msg.
We ask MSC administrators in order to ask for a signaling trace.