[comp.dcom.modems] Interesting Problem

mpd@anomaly.sbs.com (Michael P. Deignan) (07/28/90)

I've got an interesting problem with my Telebit Trailblazer Plus which
I'm wondering if anyone else has run into.

The modem will perform flawlessly on incoming calls. No problems, answers
like a charm.

However, on outgoing calls, there are times when the modem will appear
to be "deaf". That is, although I can hear a remote system's carrier,
the Telebit will sit there, not answering with a return carrier to
establish a session.

First, this started happening with only Telebit to Telebit calls, and it
will happen for about 12 hours, and then the modem will revert back to
"normal" for a week or so. Now, however, it is happening on low-speed
calls as well.

Has anyone else experienced this set of events with their Telebit. If so,
how did you correct it?

MD

csu@alembic.acs.com (Dave Mack) (07/30/90)

In article <2247@anomaly.sbs.com> mpd@anomaly.sbs.com (Michael P. Deignan) writes:
>I've got an interesting problem with my Telebit Trailblazer Plus which
>I'm wondering if anyone else has run into.
>
>The modem will perform flawlessly on incoming calls. No problems, answers
>like a charm.
>
>However, on outgoing calls, there are times when the modem will appear
>to be "deaf". That is, although I can hear a remote system's carrier,
>the Telebit will sit there, not answering with a return carrier to
>establish a session.

I've had the same problem with a T2500, at both PEP and low speeds. I
think the problem is with the phone service, not the modems. It only
happens to me when I try to place long distance calls. My usual LD
provider is Allnet. I can frequently make the connection if I use
AT&T instead. This is a bit weird, as Allnet is supposed to have
cleaner LD service - their switching system is entirely digital.

If anyone can give an explanation of what's going on, I'd appreciate
it.

-- 
Dave Mack

tts@ttank.ttank.com (Karl Bunch) (08/01/90)

In <2247@anomaly.sbs.com> mpd@anomaly.sbs.com (Michael P. Deignan) writes:

>I've got an interesting problem with my Telebit Trailblazer Plus which
>I'm wondering if anyone else has run into.
>
>The modem will perform flawlessly on incoming calls. No problems, answers
>like a charm.
>
>However, on outgoing calls, there are times when the modem will appear
>to be "deaf". That is, although I can hear a remote system's carrier,
>the Telebit will sit there, not answering with a return carrier to
>establish a session.

I had a friend that had this same problem.  It seems he put a cheap phone
on the Telebit (T2500) modem (Phone Jack on back of modem) and when you
dial-in the phone doesn't affect the connect but on dial-out it will
make your modem act deaf.

My guess is that on dial-out the relay doesn't cut the phone until last
min. whereas on dial-in it cuts the phone out when the modem goes off hook.

I have also noticed that if you plug the telebit into another device's 
(i.e.  a 2400 baud modem) out or phone connection that the device may
interfere with good communications.  I am not sure if some devices tend
to add filters etc between the Line-in and Phone-out jacks, if they do
this may be part of the problem.

One thing to try is swap modems with a friend.  If you have the chance
put the modem on another phone line.  If your pretty sure it isn't your
equipment, call your phone company.  Some phone companys can be very
helpful or a pain in the butt depending on their attitude etc.  I have
had nothing but great help in the past.  We call and complain about
problems and they go nuts with all kinds of neat testing equip.  Beware
that many charge a fee if your equipment turns out to be the problem.

Good Luck,
Karl
-- 
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