Following the receipt of a RELEASE COMPLETE message from the network, the user shall stop timer T308; release both the B-channel and the call reference, and return to the Null state.
If a RELEASE COMPLETE is not received by the user before the first expiry of timer T308, the RELEASE message shall be retransmitted and timer T308 shall be restarted. If no RELEASE COMPLETE message is received from the network before timer T308 expires a second time, the user may place the B-channel in a maintenance condition; shall release the call reference, and return to the Null state.
Note - The restart procedures contained in 5.5 may be used on B-channels in the maintenance condition.