Special Disconnection Behaviour

Usage Notes

1. The `CALLSTATUS` variable was implemented to allow notification specifically in the case of caller disconnection. Because of this restricted purpose, the `CALLSTATUS` variable has no other values that it can be assigned by the IP Media Server.
2. The `CALLSTATUS` variable will only be used if the call has been disconnected due to the caller hanging up. The `CALLSTATUS` variable will not be used if the application causes the call to be disconnected, using `<disconnect/>`. The `CALLSTATUS` variable will also not be used if the application throws the disconnect event, using `<throw event="telephone.disconnect.hangup"/>` (which won't cause the call to be disconnected anyway).