Hi Alonewolves, you mean t3101 trigger only for ghost rach? I dont think so it should be pegged for all abis related problem and so timer expiry, not only f or ghost rach i guess.. About formula, we use same formula and agai ghost rach not discarded here. I pas ted some info from google, check it out, its quite clear ha Short info for t3101: T3101 (Default 3s) When: immediate assignment process Timer T3101 is used to set the interval between the start time when an IMM ASS m essage is sent by BSC and the stop time when an EST IND message is reported to B SC. BSC releases the seized SDCCH if no EST IND message is received within the t ime specified by timer T3101. Normal flow MS ? RACH ? BSC MS ? IMM ASS ? BSC (start counting the timer) MS ? EST IND ? BSC (stop the timer) Abnormal flow 1). MS ? RACH ? BSC MS X IMM ASS ? BSC (start counting the timer) In this case IMM ASS message is not received by the MS. Then BSC will release th e seized SDCCH after waiting the time specified by timer T3101. 2). MS ? RACH ? BSC MS ? IMM ASS ? BSC (start counting the timer) MS X EST IND X BSC In this case, ESTIND message is not sent by the MS after receiving IMM ASS messa ge. The BSC will release seized SDCCH channel as above case. 3). MS ? RACH ? BSC MS ? IMM ASS ? BSC (start counting the timer) MS ? EST IND X BSC In this case ESTIND message is sent by MS. But BSC does not receive ESTIND messa ge. The seized SDCCH channel will release as above cases.