4
40-400-00001, Rev. A
Introduction
ISDN (Integrated Systems Digital Network) is a system which combines telephone
and computer networking in a digital medium. The ISDN BRI (Basic Rate Interface)
is the interface for individual users to connect to the public telephone network. An
ISDN BRI is composed of three separate channels of information called 2B+D, that
is, two full duplex Bearer channels and one full duplex Delta channel combined onto
a single pair of wire.
The Teltone ILS-1000 (ISDN Line Simulator) is two ISDN BRI connections in a
portable housing. The user interface is either a “U” or an “S/T” connection using an
RJ45 modular plug. The “U” connection is similar to the interface that is provided by
a local telephone service provider (LEC), such as one of the Bell Operating Compa-
nies, or an independent telephone company. The “S/T” connection uses a built in
NT-1 (Network Termination 1) to connect to Terminal Equipment that includes TE1s,
TAs, and TE2s. Using these connections, the user is able to place calls, either
voice or data, or both, using the National ISDN-1 signalling standard. AT&T 5ESS
Custom provisioning is available as a separate option (ILSATT-01).
ISDN is based upon an OSI (Open System Interconnection) model. The ILS-1000
supports layer 1 (physical operation), layer 2 (data link operation), and Layer 3
(network operation.) Layers 4-7 are considered application layers that use the first 3
layers as a base.
The ILS-1000 ISDN Line Simulator has been developed to make the transition from
traditional telephony to ISDN networking easier. Software developers, manufactur-
ers, integrators, and sales representatives now have an ISDN-BRI
server in a box.
The ILS-1000 supports ISDN-BRI end-to-end operation, multiple Call Control
protocols, telephony switch services, and simple functional operation on the desktop
or lab bench.