outbound serial modem now times out or drops connection

Mark Stosberg mark at summersault.com
Fri Jun 6 14:49:40 UTC 2008

> > Trying a new modem (US Robotics external 56k serial modem) did help
> > slightly. With it, we consistently connnect, but then after a short
> > pause the connection is dropped. This is easily reproduced  in
> > "minicom": (Using the Sprint TAP modem number here). 
> > 
> >   ATDT18886561727
> >   CONNECT 31200/ARQ/V34/LAPM/V42BIS
> >   
> > 
> > I'm out of ideas here. This phone line is only used for this outbound
> > service, although our alarm system also uses it for outbound alerts. 
> > 
> > Any suggestions for possible causes or further troubleshooting
> > approaches are appreciated. 
> Does that modem support Unimodem Diagnostics? What do you get from a
> '#UD' command right after the failed connection attempt?


Thanks for the response!

I tried that with Minicom, and the prompt just goes back to the hover
over the "#" sounds and sits there. From some quick Google searches, I
didn't find any mentions of this modem supporting that. 

I'm also not familiar with the details of the TAP protocol. After the
CONNECT, who should speak next? From looking at the qpage source code,
it looks like we might be waiting for "ID=" to sent from the remote end,
and it is not. 

That would make me suspect the remote end, except that multiple remote
modems are responding the same way. 


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