Did you enable the parameter “ATT” that allows a MS to perform an IMSI Attach ?
Otherwise the phone is ON, but not attached.
Second possibility: the MS was detached too early. Check that you T DETACH in the VLR (NSS parameter) is 2x greater (and a little more) than your T3212.
T_Detach = (2 x T3212)+20mn for example.
Hi, how many AGCHs you have in that cell? Check if there are to many declared. If few paging channels then you might experience unreachable case.
Regards,
Rex.