From: [email protected] (Lars Poulsen)
Subject: Re: Where can I find specs on Digital PBX interface?

At 09:33 AM 4/14/97 -0700, John van Heteren <[email protected]> wrote
   on the TREG mailing list:
>  I am told that several years ago the vendors of 
>digital PBX systems reached an agreement on the 
>hardware and software interface to their systems.
>In this way, people could make their own telephony 
>equipment to link to the PBXs.

There is indeed such a specification, which is widely used by several
manufacturers, but it is still a minority of telephone system vendors
that build to this open standard (The Basic Rate Interface for Digital
Telephony.)

This open standard is known as ITU specification Q.921/Q.931, and
additional detail is provided in various supplements from ETSI
(CTR 3 series).

 - - -

So why do most vendors prefer to build to proprietary interfaces instead
of building to open standards ? Because it allows them to shift the
price from the switch to the station sets. If the station interface was
an open standard, prices would have to be competitive on each component.

/ Lars Poulsen               [email protected]          +1-805-562-3158
  OSICOM Technologies (Internet Business Unit)       (formerly RNS)
  7402 Hollister Avenue        Manager of Remote Access Engineering
  Goleta, CA 93117                Internets designed while you wait

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