I think the Message “network Initiated Realease” is related with the RLINKUP Parameter:
RLINKUP is used by the BSC to
determine when to disconnect the call upon repeated failure in decoding the SACCH.
A counter that is given the value
RLINKUP is started in the BSC
after the assignment of a dedicated
channel. Two units increase the
counter if the SACCH data is
One unit decreases it if it can not be successfully decoded. If the counter reaches the value zero, then a call release is initiated.
Is possible, when you cannot decode the sacch data is related with interference (cochannel or adj channel) or may be that you are using a wrong MAIO (when you´re using Hopping)….