SDCCH drop counter pegs due to Radio reason at the moment of Ciphering phase. But we dont know where exactly in Ciphering.
A trace was done by Core guys but nothing found abnormal as they said due to they dont have a tool for A trace anaylsis, they did it in text I think. so nothing come up.
If we find which message not send/arrive in Ciphering , then what? it means something?
Exp. fail at BTS > MS : Ciphering Mode Command..