Administrator's Guide

ISDN service
Issue 5 October 2002 1737555-233-506
Call-by-Call Service Selection
Call-by-Call Service Selection for NI-2 is essentially the same as that for the
AT&T Switched Network ISDN-PRI protocol.
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 MultiVantage 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 61. 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.
Figure Notes
1. Call from network to Switch B
2. ISDN trunk
3. Switch A
4. Non-ISDN trunk
5. Switch B