Re: PSTN over PRI for ISDN?

Marty Likier (marty@livingston.com)
Tue, 13 May 1997 07:49:34 -0700

At 03:53 PM 5/12/97 -0700, Leonard wrote:
>Hi,
> we're taking PRIs into a dual pri PM3. We're considering dedicating
> one of the PRIs to handle only ISDN BRI calls. I dunno if the mainboard
> processor of a PM3 can handle such loads (1 PRI all ISDN and 1 PRI all
> analog), but I have a more immediate concern:

No problem. The main CPU is assisted by HDLC controllers, and a fast and
wide data bus. And from a real world perspective, I have not heard of any
performance issues related to handling in an all isdn environment.

> Our local telco insists that we need to ride PSTN over the PRI.
> I can understand the need to do that for analog calls, but they insist
> it's also needed for ISDN BRI calls. They're explaination is that
> the PRI comes "as is" without any telephone number, and that we still
> need the PSTN for the telephone number to overline (1 per B channel).
> I was wondering if anyone has gotten their PRI to handle ISDN calls
> without any PSTN on it. We're paying a nuclear bomb for the PSTN (more
> than twice the PRI cost).

This sounds pretty hoakey. (did I spell that right?) Generally you can
request service for either alternating circuit-switched voice and data, or
circuit-switched data. Alternating circuit-switched voice and data permits
ISDN and modem calls. Circuit-switched data permits only ISDN calls.
Usually alternating circuit-switched voice and data commands a premium from
the telco. In either case, both services come with a telephone number. ;-)

--
Marty Likier
Product Marketing Mgr.
marty@livingston.com