Wideband Signaling
Issue 5 January 1998 12-21555-230-024
Distributed Communication System nodes are connected by tie trunks (us ing
DS1 and ISDN-Primary Rate Interface facilities, for example). In addition, a data
link is provided between the various nodes (additional equi pment such as a data
module may be required), offering selected feature transparenc y across the net-
work. With ISDN-Primary Rate Interface, the data link can be configured to use
either a B-Channel or D-Channel. In Figure 12-2, Te lephone A calls Telephone B
and then sets up a conference with Telephone C; certain system features operate
as if the telephones were all on the same switch.
DEFINITY ECS’s Distributed Communication System features a sophistic ated
rerouting capability for optimizing trunks. Thus when you transfer out of your
AUDIX voice messaging system, for example, DEFINITY ECS sets up a new path
that optimizes system resources.

Distributed Communications System and ISDN

To support DCS customers who also have ISDN-Primary Rate Interface, DEF IN-
ITY ECS can transport DCS messages over ISDN-Primary Rate Interface D chan-
nels. As a result, you are not longer limited to pri vate-line connections between
your various locations. You can also use public network s ervices.
Software Defined Network supports all DCS features except the following:
■DCS attendant control of trunk group access
■DCS attendant direct trunk group selection
■DCS busy verification of terminals
All other capabilities and limitations associated with the DCS still apply. T his
allows your company to enhance network functions by adding the benefi ts of
ISDN QSIG.
DEFINITY ECS also supports networking between the DCS signaling on the ISD N
D channel and the DCS signaling on traditional signaling links. AUDIX system s
network via DCS can also be supported over ISDN-Primary Rate Interface.
Wideband Signaling
DEFINITY ECS’s support of wideband signaling allows the system to handle
applications with transmission rates greater than 64 Kbps i n a single call. This
includes videoconferencing, Local Area Network bridging, and othe r wideband
applications. The system switches wideband data at N x DS0 data rates — a
standard for international networking.
Systems with only narrowband capabilities typically handle wideband trans mis-
sions by splitting the data stream into several calls. Advantages of wideband s ig-
naling support include: