# Comcast Digital Voice. Help Please!



## escapexls2001 (Jul 10, 2007)

Hello everyone,

I am new to the site and love it so fare. I am having a problem with my Comcast Digital Voice, and was wondering if someone who knows more about it than I do could answer a few questions.

I have comcast high speed internet, as well as the digital voice. I had a power outage yesterday. When the power was out my wired phones worked fine, since the modem has a battery in it. However, when the power came back on, none of my phones were working!
My internet works perfectly fine. I did troubleshooting steps with tech support over the phone and we found that when I plug a phone directly into the back of a modem I will get a dial tone and everything works.

The tech on the phone thinks there is a short circuit somwhere in the house wiring. My main question is that where does the digital phone service hook into my house wireing??? I wasn't home when it was installed. From what I heard the instalations man never went into the basement where the main connections are. I just don't understand how my digital voice modem connects to my house's normal wired phones, besides the connection directly in the back of the modem???? If someone could explain this to me I would very much appreciate it! Thank you!


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## JohnWill (Oct 19, 2002)

I suspect what happened is they just plugged it into a phone jack near the installation. If you didn't disconnect the home wiring from the telco service entrance, that could be why the phones aren't working. You need to make SURE that the house wiring does NOT connect to the old telephone company lines.


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## escapexls2001 (Jul 10, 2007)

Comcast came out, and what happened was when my power was restored, there was mostl likley a surge that went through the phone lines and shorted out a jack in a different room. This short caused all of the homes phones not directly connected to the modem to not function.

I'm still curious as to how this setup works. The was I understand it now is that plugging the comcast digital modem into any phonejack in the house enables all of the phones in other rooms to work on the system???


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## JohnWill (Oct 19, 2002)

Phone wiring is daisy-chained to all the phones, they're in parallel on the phone lines. Any jack has the same connection as any other. That's why they all work when you simply plug the VoIP into a jack. I have Vonage VoIP here, and I did the same thing.


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## westcoaster (Jul 21, 2007)

I am an installer/troubleshooter. As you already know your dial-tone is generated from the back of the modem or EMTA. The phone line extending from the back of the modem and to
the phone jack is backfeeding to the NID ( Network Interface Device) also called the Demarcation point, which usually is a small gray box on the garage side of the house. Inside
this box is a customer access point that houses the input from your previous telephone provider which should be disconnected at this time. Now, the phone line that is coming from
the room with the modem should be connected to the posts inside the NID to transfer dial tone to all the remaining phone lines in the house. Hopefully that backfeed line is marked in the event a tech needs to come out later and troubleshoot. 
NOTE: This is a general scenario and Comcast wiring would be different if you have a monitored home alarm system. Do you know if your phone wiring in the house is a
loop-system or does each jack location have a dedicated line coming from the NID?


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## abelleba (Jun 29, 2008)

If you need help understand how the back feeding part works you can read this link has instructions for homes with or without alarms.

lurker,


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## JohnWill (Oct 19, 2002)

A telephone connected alarm poses unique issues, since many of them won't function with a VoIP connection. In addition, you may lose your phone connection when power is out...


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## abelleba (Jun 29, 2008)

This is somewhat true. In my two years of experience (installing) there was not a single alarm I could not wire VoIP too. Some took a bit of tweaking than others but I never was failed by it. I worked for Comcast, that had a 12 hour back up battery in their device with a option to purchase a second 12 hour battery (24) hours. Power is no longer a issue with new VoIP Hardware technology.

Regards,


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