Avaya Communication Manager Administrator's Manual page 1623

If a user connects 2 trunks through conference or transfer, and neither far-end media server or
switch on the resulting connection provides disconnect supervision, the trunks involved will not
be released because Avaya Communication Manager cannot detect the end of the call.
Communication Manager will not allow trunk-to-trunk transfers unless it believes that at least
one party on the call can provide disconnect supervision. Therefore, setting this field incorrectly
might cause trunks to become unusable until the problem is detected and the trunks are reset.
Valid entries
y
n
!
CAUTION:
In general, U.S. central offices provide disconnect supervision for incoming calls
CAUTION:
but not for outgoing calls. Public networks in most other countries do not provide
disconnect supervision for incoming or outgoing calls. Check with your network
services provider.
Disconnect Supervision-Out
This field indicates whether Communication Manager receives disconnect supervision for
outgoing calls over this trunk group. It appears when the Direction field is either outgoing or
two-way. (If the Direction field is incoming, Communication Manager internally sets this field
to n.)
The entry in this field is crucial if you allow trunk-to-trunk transfers. (To allow trunk-to-trunk
transfers involving trunks in this group, this field must be y and the Trunk-to-Trunk Transfer
field on the Feature-Related System Parameters screen must be y). If a user connects 2
trunks through conference or transfer, and neither far-end server/switch on the resulting
connection provides disconnect supervision, the trunks involved won't be released because
Communication Manager can't detect the end of the call. Communication Manager will not allow
trunk-to-trunk transfers unless it believes that at least one party on the call can provide
disconnect supervision. Therefore, setting this field incorrectly might cause trunks to become
unusable until the problem is detected and the trunks are reset.
Usage
Enter y to allow trunk-to-trunk transfers involving trunks in this group.
Enter y if the far-end server/switch sends a release signal when the
calling party releases an incoming call, and you want to make the far-end
server/switch responsible for releasing the trunk.
Enter y to enhance Network Call Redirection.
Enter n if the far-end server/switch doesn't provide a release signal, if
your hardware can't recognize a release signal, or if you prefer to use
timers for disconnect supervision on incoming calls. Entering n prevents
trunk-to-trunk transfers involving trunks in this group.
Trunk Group
Issue 2.1 May 2006 1623