Feature Reference
ISDN service
Administrator’s Guide for Avaya Communication Manager
1585
November 2003
ISDN interworking
ISDN interworking allows calls to use a combination of both ISDN and non-ISDN trunking and station
facilities. A non-ISDN trunking facility is any trunk facility supported by the system that does not use the
ITU-T recommended Q.931 message set for signaling. Non-ISDN trunking facilities include facilities
such as analog trunks, AVD DS1 trunks, and DS1 trunks with bit-oriented signaling (robbed-bit or
common channel).
Avaya Communication Manager supports the conversion of ISDN signaling to non-ISDN in-band
signaling and the conversion of non-ISDN in-band signaling to ISDN signaling for interworking
purposes.
A mixture of ISDN and non-ISDN signaling is required in order to provide end-to-end signaling when
using different types of trunk or station facilities on a call. See the figure below for an example of
interworking.
Figure 394: ISDN and non-ISDN interworking
In this example, a call for someone at Switch B comes into Switch A. Interworking allows the ISDN
signaling of the call to be converted at Switch A to non-ISDN in-band signaling before the call forwards
to Switch B. Even though the call comes into Switch A on an ISDN trunk, Switch A can send the call to
Switch B over a non-ISDN trunk by converting the signaling information.
The system provides accurate CDR billing information on calls that are not interworked. Accuracy of
CDR billing information on interworked calls is equivalent to the accuracy provided by the public
network.
Communication Manager supports sending a non-ISDN trunk name as the connected name. Therefore, a
non-ISDN trunk name can be sent as the connected name even when a call starts out as an ISDN call but
is interworked over non-ISDN trunks.
Figure notes
1
Call from network to Switch B
2
ISDN trunk
3
Switch A
4
Non-ISDN trunk
5
Switch B