[comp.dcom.telecom] Phone Line Simulator Needed to Test Modems

joseph@milton.u.washington.edu (Joseph Chan) (03/19/91)

We got several V32 9600baud modems.  I have not got them to talk at
9600 baud rate.  They work at 2400 baud.  I suspect that the phone
line (we had) may have trouble to connect at 9600 baud.  To determine
this, I would need a simple phone line simulator, such that I can
connect two modems together with go through the local phone line.
Could anyone show me how to make a simple phone line simulator?  Thank
you.

mark@uunet.uu.net (Mark Oberg) (03/23/91)

In article <telecom11.218.7@eecs.nwu.edu> joseph@milton.u.washington.
edu (Joseph Chan) writes:

> We got several V32 9600baud modems.  I have not got them to talk at
> 9600 baud rate.  They work at 2400 baud.  I suspect that the phone
> line (we had) may have trouble to connect at 9600 baud.  To determine
> this, I would need a simple phone line simulator, such that I can
> connect two modems together with go through the local phone line.
> Could anyone show me how to make a simple phone line simulator?  Thank
> you.

I once wanted to do something similar and found that if I connected
the two modems together with a RJ-11 type cord I could get them to
talk to each other by placing each modem on it's own terminal program
(and computer) and instructing one modem to "ATO" (Hayes for go
online) and the other to "ATA" (Hayes for answer a call).  The two
modems will send their carrier and handshake sequence, connect, and
you can send data between them.  No need for a phone line simulator;
just a phone cord.


Mark Oberg - Voice: Northstar Telecom, Inc.  (301) 964-0505
UUCP: uunet!grout!mark
Fidonet: 1:109/506 & 1:261/1067 
BBS: No Place Like Home - (301) 596-6450 & (301) 730-9072

peter@taronga.hackercorp.com (Peter da Silva) (03/25/91)

I would like to note that if your phone line is hostile to V.32 9600
baud connectios, you might try Telebit Trailblazers. They connect at a
nominal 19200 baud, and the actual transfer rate is 18000 baud down in
100 baud increments until they find a set of frequencies they can live
with. This is before any compression is applied to the connection.

The only places I've found that faze Trailblazers are London, England
and some Sprint long-distance connections.


peter@taronga.uucp.ferranti.com