[comp.dcom.telecom] AT&T Modem Calls Succeed; Other Carriers Fail

sba8_ltd@uhura.cc.rochester.edu (Scott Barnes) (10/31/90)

Over the past few months, I have been unable to place modem calls
using Least Cost Route (LCR) long distance on our Rolm CBX 9000 PBX.
The calls do complete, but the local and remote modems usually refuse
to handshake.

This probably sounds like a typical modem failure, but there is a
twist to the problem.  Explicit AT&T credit card modem calls are
successful, as are local calls.  I have duplicated this situation
several times using different modems.  The problem seems to lie
somewhere outside the Rolm system, but I have been unable to put my
finger on it.

Is is possible that one of the LCR carriers has an entire rack of
faulty equipment (i.e., distorting the frequency of the call)?  Would
the LCR trunks be distinct from AT&T and local trunks in the Rolm
system?  Any clues or assistance would be appreciated, as I would like
to know what I'm talking about before I report this problem.


Scott Barnes
University of Rochester
sba8_ltd@uhura.cc.rochester.edu

BRUCE@ccavax.camb.com (Barton F. Bruce) (11/02/90)

In article <14182@accuvax.nwu.edu>, sba8_ltd@uhura.cc.rochester.edu
(Scott Barnes) writes:

> Over the past few months, I have been unable to place modem calls
> using Least Cost Route (LCR) long distance on our Rolm CBX 9000 PBX.

> Is is possible that one of the LCR carriers has an entire rack of
> faulty equipment (i.e., distorting the frequency of the call)?  Would
> the LCR trunks be distinct from AT&T and local trunks in the Rolm system?  

There are all sorts of possible problems, but you need to ask your
admin. who the other carriers are and HOW they are connected to your
switch.

If there is a leased T1 line to their POP, and if some 'clever' chap
decided that 44 ADPCM voice channels was a better choice than 24 PCM
ones, that IS your problem.