Phone wire problem
 

We think we have a short in the phone wiring in our house. The phone works at the modem but the other phones in the house do not work. Do we call Comcast or an electrician? Suggestions?

I believe that the wires to all of your outlets are not tied together where the Telco enters the house. If they were, and you had a short, nothing would work. Check at the box ( may be outside or in garage) where the wiring to all of the outlets appear to see if they are bridged together. Was Comcast supposed to activate all outlets?

Make sure the telephone wire from the modem to the phone jack is plugged in. The phone backfeeds from this point.

Unplug all your phones and systematically swap them out.
You know the jack at the modem works. So plug each phone in there and see if you have a problem on any of the actual phones. Then take the phone that is currently plugged in at the modem ( which you know works) and test it in each jack to see if you have a jack problem.
I'm betting it's one of the phones.

do you have DSL filters on all the phone lines?

Thanks to all for your suggestions. Turns out it was the outside box but there was also a line problem. The first Comcast tech called in the troops. In all, four Comcast trucks and four Comcast techs were engaged this afternoon. Kudos to Comcast for persevering and solving the problem.