Alcatel Unleashed

The call is not released after depositing a voice message into mailbox through analog trunk. The disconnection tone is also added with voice message. This is ok in case of if incoming call is made through PRI and also for extension to extension.

For analogue line - PBX usually not detect disconnect (just busy tone).
You can try to manage "busy tone detection" for TG. Or use external devices (detect busy tone and send "disconnect" to PBX)