remote transcoder system drops are detecte due to loos of synchro between BTS and TC. Therfore, anything in between can be the problem :
SUM fail – ABIS fail – BSC/ABIS board fail (TCU) – BSC/ATER board fail (DTC) – ATER fail – TC board fail
I recommend you check which sites are having RTC drops, and ind what is the common equipment between them : BSC ? TC ? Abis ?
Most of the time, it has to do with Abis failures (if only all cells connected to this Abis are impacted), or BSC board failures.