hacking old telephone lines.
January 5, 2010 11:46 AM   Subscribe

Home telephone wiring is a rats' nest - I want to move an old line to my VOIP connection, using existing home wiring. Help!

So the old twisted-pair telephone wiring in this place is a total rat's nest. We're talking 75 years of runs, re-runs, retrofits, hacks, splices, etc.

I have two lines that I want to conflate to one:

1. My VOIP line, provided by my cableco. Cordless phone is plugged directly into the cable modem.

2. My old land-line - I'm pretty sure I know where the connection is coming into the house (there's a *lot* of twisted pair around here). Currently hosts my fax machine (in another room, a *long* way from the cable modem), and an old answering machine to catch any calls still being made to that line.

What I would love to do:

1. Stop paying for the land-line (I'm not using it any more), get the telco to disconnect service (I'm considering having cableco take the # over, and just forward calls to the existing VOIP line).

2. Plug VOIP line into the existing home wiring - there's an RJ11 jack near my VOIP line that I know is part of the same wiring the fax machine is connected to.

3. Connect the fax machine to the VOIP line via said home wiring.


Someone who's done battle with twisted pair - this seems totally reasonable, but what are the pitfalls? Once the telco disconnects service, can I simply plug the VOIP line into the nearest RJ11 jack, or do I need to do more than that?

PersonalSkillLevel: I've got a voltmeter, I (sort of) know how to use it, and I'm not afraid to cut/strip/crimp wires. I have a rough idea of how the physical twisted-pair system works.

Thanks in advance!
posted by swngnmonk to Technology (9 answers total) 2 users marked this as a favorite
 
Man, I'd love to do this as well, and my house was built in the 40's, with an equally ridiculous mess of phone wires. If you find a guide to understanding the telephone wiring, pleas post it here.
posted by exhilaration at 12:25 PM on January 5, 2010


I am having difficulty parsing this. The telco provides dial tone. The cableco provides a network path. The fax machine uses dial tone and, I expect, is not a networkable device. Wiring for dial tone can be either in a star or daisy chain configuration. Ethernet networks are a star configuration.
posted by llc at 12:35 PM on January 5, 2010


I have a VOIP box (Ooma) and I can simply plug the unit into any RJ11 jack and get service for the rest of my house.
posted by wongcorgi at 12:41 PM on January 5, 2010


Most houses are wired so that all of the phone connections are wired TOGETHER. That means if you plug your VoIP adapter into any phone connection, all of the others should work.

What is very important is that you disconnect the telephone company's connection from your wiring. This is usually done in a little gray or green box on the outside of your house. You don't want both the Telco and your new VoIP box connected at the same time because it will likely ruin your VoIP box.

I only pay $1.50 a month for my VoIP line. It pays to shop around. I recommend dslreports.com VoIP forum for suggestions.
posted by Witherwings at 12:52 PM on January 5, 2010


Call your cable company--they may/should be able to handle this situation.

Hopefully your RJ11 (6P6C) wall jacks all tie back to a single location. Your cable modem (also a phone modem) can provide the dial tone for the whole house.

Cox Cable came over did the following with my 50s-era house in Alexandria, VA: They ran a line outside from my cable modem (which provides a POTS dial tone by means of a modem, so you can use a regular phone like your cordless phone) to the central switch box. Because all the phone jacks were wired in parallel, you could plug in any POTS phone to any jack in the house and get a dial tone and service just as though it was plugged into Ma Bell's own.

I remember the cable modem had two phone jacks for if you signed up for two separate lines; that would mean running another line from the cable modem to the switch box and wiring it to the 'other' line that the 'other' jack(s) were wired through.

Your cable modem is a combination device that 1) handles data for networking computers to the internet, which you plug a router into and 2) acts as a bridge between ordinary phones, obsolescing the standard phone company and their landlines.

One gotcha is that if you plug your cable-phone-modem-thingy into the wall (parallel as wongcorgi says) it will work..sorta. You need a crossover cable if you're doing this, which is to say the center conductors of the RJ11/6P6C, numbers 3 and 4, need to be crossed. Otherwise you may have weird occasional line trouble.

I'd just call the cable company - they'll get you sorted out.
posted by ostranenie at 1:01 PM on January 5, 2010


This guide to hooking up VoIP to your existing phone jacks from Vonage is pretty much the horse's mouth on the subject.

Summary: be sure to physically disconnect the phone company's wiring from your home's wiring at the point where the two interface, and then just plug the phone output of your VoIP adapter into one of the wall jacks with a normal phone cord.

The two caveats you need to be aware:

* VoIP adapters can usually only power a handful of phone ringers (ie, 4 or 5), so if you have a large number of phones, that may be a problem.

* Faxing over VoIP, if the VoIP service you receive is highly compressed, may not work well. It's not impossible to fax over VoIP, but quality varies depending on the technologies in use and the VoIP provider you use. I would strongly recommend testing your fax machine over VoIP, both sending and receiving, before you decide to cancel your landline service.

Depsite what ostranenie says, you don't need a crossover cable for this.
posted by eschatfische at 1:18 PM on January 5, 2010


For about $20-$40 U.S. you can get a cable tracer to help you map out your various lines. I got this one, Amazon.com: Gardner Bender GET-4110K Wire Tracker, from my local hardware store. Has helped me numerous times with the rats-nest of twisted pair lines and coax throughout my house. The one I own has various connectors - RJ11 RJ45 Coax and alligator clips - that allow one to use it for just about any non-powered lines. There is some crosstalk in bundled wires, but you get an obvious signal when you get to the correct wire.
posted by crenquis at 2:07 PM on January 5, 2010 [1 favorite]


Response by poster: Everyone - thank you for the quick response!

Unfortunately, now the challenge is the various providers - my cableco is providing my VOIP line, and they want an insane amount of money to take over my POTS line.

Time to find a new VOIP provider.
posted by swngnmonk at 2:20 PM on January 5, 2010


You may or may not need a crossover cable for this. The cable guy was adamant that I needed one for my installation and that it would cause intermittent problems if it was not wired this way. I didn't understand why, but we never had any problems with the phone service. I'd ask.
posted by ostranenie at 5:52 AM on January 6, 2010


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