On Wed, 2 May 2001 12:12:28 -0500 (CDT)
"mjn" <mjn at umn.edu> wrote:

> 
> Yea.  Murphy's kicks in when you are downloading a Linux image and the
> phone rings and your DSL modem mysteriously drops its connection.  Every
> time the phone rings...

Interesting, when a phone rings the impedance it presents to the line
changes due to the reactance of the bell circuit (which has both inductive
& capacitive reactance components, the bell is essentially a simple AC
coil in series with a .47uF capacitor, at least on a mechanical telephone
set). This really shouldn't affect the DSL service. One possibility
though, is that you have a damaged ringing capacitor (or coil?) somewhere,
that manifests a DC short when it passes the ringing current... If the DC
resistance drops too far, this will kill any AC signals at _any_ of the
frequencies we are dealing with. Also, electronic telephones with
oscillating ringers can have very odd effects under ringing load, so they
might be suspect.

Have you considered removing all of the analog telecom devices on the
line, then having someone 'ring' in (you won't hear it obviously) and see
if it still dumps the connection? If it doesn't, it's safe to say that the
issue is related to one of the analog devices, and more specifically it's
reactance. Troubleshoot by adding them back in one at a time. If
connections still drop, I would suspect that somehow the ringing voltage
is affecting the modem, which would tend to indicate a defective modem..? 

Also, are you sure that you might not have a filter in backwards
somewhere? My DSL serivce worked for several days, and then mysteriously
went down - the cause was a backward filter. I'm not sure what 'changed'
to make a previously acceptable condition suddenly a cause for failure.

BTW, I do not have this problem :))

                           -.bill.layer.-
                          
-.those who are talking don't know, and those who know aren't talking.-

           -.frogtown.-     -.minnesota.-      -.u.s.a.-