When in-band tones/announcements are provided (see 5.4), the DISCONNECT message contains progress indicator No. 8, in-band information or appropriate pattern now available.The network shall: start timer T306 and enter the Disconnect Indication state.
On receipt of the DISCONNECT message with progress indicator No. 8, the user may connect (if not already connected) to the B-channel to receive the in-band tone/announcement; and enter the disconnect indication state. Alternatively, to continue clearing without connecting to the in-band tone/announcement, the user shall disconnect the B-channel; send a RELEASE message, start timer T308 and enter the Release Request state.
If the user connects to the provided in-band tone/announcement, the user may subsequently continue clearing (before the receipt of a RELEASE from the network) by disconnecting from the B-channel;sending a RELEASE message; starting timer T308; and entering the Release Request state.
On receipt of the RELEASE message, the network shall stop timer T306; disconnect and release the B-channel; send a RELEASE COMPLETE message; release the call reference, and return to the Null state.
If timer T306 expires, the network shall continue clearing by disconnecting the B-channel; sending a RELEASE message with the cause number originally contained in the DISCONNECT message; starting timer T308, and entering the Release Request state.
In addition to the original clearing cause,the RELEASE message may contain a second cause information element with cause No. 102, recovery on timer expiry; this cause may optionally contain a diagnostic field identifying the timer that expired.
On receipt of the RELEASE message, the user shall act according to 5.3.3.