[HELP] using existing POTS wiring


#1

I tried in IRC but got no response…
I have VOIP service from Time Warner that enables me to run a telephone cord from my cable modem to any POTS jack in my home. This “energizes” (Time Warner’s word, not mine) the existing POTS wiring so I can use any POTS jack with an analog phone in the house with the VOIP service. Is something like this possible with a TDM400P card? Or will I have to plug any analog phones I want to use directly into the card?

Thanks in advance for any help.


#2

I believe Time Warner’s phone service does nothing more than provide you with a standard analog dial tone. I called them in my area and they were very cautious about their service not being VoIP. I suppose this is to avoid some sort of FCC regulation (or taxes).

So, to answer your question, “yes” that is very possible with the TDM400P card. You would need a FXS module to generate dial tone, then connect that line into a phone socket on the wall, then all other phones in your house will be using that FXS line (provided they are on the same line).

Digium’s explanation of FXO and FXS
digium.com/index.php?menu=fxsvfxo

However, if you want to setup a home-based test system for the Asterisk software, you will only NEED a TDM400P with a FXO module, because you just want to tap into the dial tone provided by Time Warner. From there, you can run SIP hard phones for your extensions, or Soft-Phone software, on any computer at your house.

Then again, if you want an easy way to use existing analog phones, while you puzzle out the wonders of Asterisk, you can get a TDM400P with one FXO and one FXS module ( store.digium.com/product_view.ph … de=RTDM11B )

Now, if $241.00 is too much to drop for just playing around with VoIP, there may be other solutions available. Have you installed Asterisk on a system yet? If so, did you get the test dialer to call the Digium PBX? If so, did you setup a SIP softphone on another computer and dial your asterisk server? I only ask these questions because, for me, these were the building blocks of my interest into VoIP.

Anyway, I hope this helps, and be aware that my information is far from professional.

Lortz
"off and on asterisk user"


#3

You can certainly extend an FXS port to any location in your home. Be careful about overloading the port with too many stations.

An FXS module can only be expected to ring a few phones. Driving a great deal of them may not be possible.

Additionally, keep in mind that the length of the wiring may be limited. Line losses can be heavy if you’re running your wring hundreds of feet.

If you’re keeping your connections in an average home (less than say 50 feet) you should have no problems.

Technically, the service from Time Warner isn’t really VOIP. It’s a radio frequency signal that’s similar to your cable TV box. It’s actually more proper to think of the service as closer to a wireless phone that doesn’t use antennas, but rather connects it’s signal through cable TV wiring instead. It’s using the DOCSIS protocol.


#4

From what I’ve read, you must be careful to NOT plug an FXS port into a phone circuit that is connected to the PSTN. Doing so will supposedly fry your FXS port.

Here’s a good reference on wiring your house for VoIP: michigantelephone.mi.org/distribute.html


#5

Thanks very much everyone, very insightful. I haven’t actually set up an asterisk box, that’s next week. I was just trying to get some preliminaries out of the way. My plan was that if it is possible to have that sort of functionality I would cancel the Time Warner altogether and disconnect any PSTN connectivity, basically just have my home wiring be a closed circuit for use with an FXS module.