[comp.dcom.modems] Help with international modem connection

dias@iris.ucdavis.edu (Gihan Dias) (11/09/90)

Hi,

I have been trying to connect with a site in Sri Lanka from the U.S.
using 2400 b/s V.22bis modems (Everex 24+) on both sides and am having
problems in connecting.

The remote modem (in Sri Lanka) answers and I hear carrier but sometimes
I don't get a CONNECT message, and sometime I do get a connect message
but can't transfer any data (not a single byte). This happened both with
MNP4 on and off (MNP5 was always off).

The connection appears OK, a bit noisy and with satellite delays and echoes
but voice communication is no problem.

O.K., the question is: What am I doing wrong? What should I look out
for and what parametes of the modem should be set for this type of
circuit. A side question: What does the guard tone do? Should I turn it
on?

Thanks for your help,

Gihan

bruce@ccavax.camb.com (11/11/90)

In article <7955@ucdavis.ucdavis.edu>, dias@iris.ucdavis.edu (Gihan Dias) writes:
> A side question: What does the guard tone do? Should I turn it
> on?

If it is what I think it is, it inhibits echo suppressors that you very much
do not want in your connection. They are switch gain repeaters that perform
an electronic push-to-talk function leaving the signal path in the opposite
direction attenuated. Certainly try turning it on.

The newer active echo cancelers used on satelite circuits are probably a 
different issue. They are also what is built into the v.32 modems to allow 
full use of the bandwith both directions at once.