INTEGRATED SERVICES DIGITAL NETWORK - PRIMARY RATE INTERFACE
(ISDN-PRI)

PRODUCT DESCRIPTION:

ISDN-PRIMARY RATE INTERFACE (ISDN-PRI) offers the customer a set of standards
which provides end-to-end digital transmission over a single access line.  It
is composed of 23 B channels and one D channel.  For this reason, it is often
referred to as 23B&D.  The PRI speed is 23 "B" channels at 64 Kbps and one D
channel at 64 Kbps.

Functions of ISDN-PRI Service:

-     Provides 23 full-duplex 64 Kbps B-channels and one full-duplex 64 Kbps
      D-channel.

-     Intended for users with greater capacity requirements.

-     Provided over a four-wire T1 circuit between the customer's premises
      and the central office.

-     Designed to be used in any application where multiple network
      connections would be appropriate today, such as a:

      -    PBX.
      -    Multiplexer.
      -    Data switch.
      -    Any other device capable of controlling large numbers of B
           channels.
      -    Individual channels are switchable.  The service provides digital
           access to the public telephone network, which then deals with
           individual connections dynamically.
      -    The 23 B-channels could be standard voice calls or a mix of
           switched voice, virtual private lines, packet-switched data,
           circuit-switched data, or video.
      -    B-channels can be aggregated to increase bandwidth (when
           higher speeds are required).

ISDN-PRI is primarily used to access the central office from a PBX, but can
also be used to connect a multiplexer, LAN or mainframe to the public
switched network.

This technology provides for the dynamic allocation of the individual
channels on a call-by-call or time-of-day basis, reducing the trunking
requirement needed to access the network.  Used as a tie line, PRI provides
for feature transparency between like vendor CentraNet/PBXs.


APPLICATIONS:

-     Connection of PBX systems to PSTN for voice transmission.
-     Connection of cluster controllers to PSTN for data transmission.
-     Connection of LANs and hosts.
-     Connection of multiplexers to the PSTN.

For more information, call 1-800-483-4927 M-F 8am - 8pm eastern.

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Copyright 1994 GTE Telephone Operations
All rights reserved