>I have an ISDN modem that I cannot get to work.  It was working until
>about last Thursday.  The repairman came out, check the line and said
>it was my pc.  We did connect the modem to two different labtops where
>the modem worked, but it still would not work with my pc.  After the
>repairman left, I plugged a 56k modem into the same comm port and the
>56k modem worked great.  This leads me to believe that the ISDN modem
>is not functioning right.  Also it does not work on my laptop now.
>I have deleted and reloaded the drivers and even the comm port.
>One question is:  Is the connection of an ISDN modem treated different
>by a PC then a 56k modem?

The connection between the computer and most ISDN modems are the same.
They usually use a subset of AT commands that 56K modems do. You
did not specify what brand/model ISDN modem you have, that information would
help.

I suspect something with the ISDN modem itself. Configuration of the ISDN
modem itself to the phone line is quite different than a 56K modem. The
ISDN modem must be configured to the specific line. The ISDN line has
identifying numbers called SPID's (Service Profile ID) and a switch type.
The modem must be programmed with this information to work properly. There
should be some kind of configuration utility that came with the modem to do
this. Most modern modems can query the line for the SPID and switch type. I
have a 3com Impact IQ, and it can do this.

There might be a couple of reasons why it all of a sudden quit working. One is
that the modem died. Another is if it lost the SPID and switch type
information, or the phone company changed it on you, so you need to re-program.
My ISDN modem quit working inexplicably about a year ago, then I realized
that we had a geographic area code split, and my SPID's naturally changed (the
SPID's usually are the phone number of the line itself), so I simply had to
re-program the modem to the new SPID's, maybe this happened to you?


Russ Poffenberger               Engineering Specialist
Schlumberger Technologies ATE   DOMAIN: [log in to unmask]
1601 Technology Drive
San Jose, Ca. 95110             Voice: (408)437-5254  FAX: (408)437-5246

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