outbound serial modem now times out or drops connection

Bob McConnell rvm at CBORD.com
Fri Jun 6 14:02:19 UTC 2008

Mark Stosberg:
> We are using qpage to dial a remote TAP modem (Sprint and Verizon), so
> we can send pages about our hosting infrastructure without using the
> internet connection. 
> Recently it started failing consistently with "timeout to connect".
> I first suspected the remote modem (Sprint), but found I got the same
> result with other carriers. (And Sprint denied a problem on their
> I have since tried a whole battery of approaches including having the
> phone line checked by the local phone company, trying a different
> and trying a different phone cord. 
> 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
> 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?

Bob McConnell

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