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Converting existing cat5 telephone lines to dual network/phone

  • Last Updated:
  • Dec 12th, 2009 10:53 pm
Deal Addict
Dec 1, 2003
1286 posts
pshch wrote:
Dec 11th, 2009 6:01 pm
How many pairs your cable has? Usually they came as either 2, 3 or 4 pairs. If you are lucky and you have 4 pairs you can have a phone and 4 network locations in the house (central point will have 3 jacks and each will be connected to the switch/router and other 3 - single jack through the house). To do this you will have to interconnect 3 matching pairs in telco box - so cable which runs to you central location will have all 4 pairs used and other 3 cables just 2 pairs - one for network and one for the phone. In theory this should and probably will work (I even use cat3 between my PC and WDTV box and getting 6-8MB/s). But because you are mixing phone and several network connections inside the same cable quality won't be impressive especially when you are on the phone and just using G wireless network may be not much more expensive but provide comparable speed and better flexibility.
very confusing....

anyways back to the original poster

yes it can be done and works fine.

With standard cat5e you can have a 10/100 network and 2 phone lines off a single cat5e cable as network only uses 2 pair.

Is there anyway you can pull those lines from the demarc back into the house where the elec panel is or is the demarc box on another side of the house? You mentioned your basement is finished but they usually install the demarc on the leg of the meter base which is where the panel usually resides (not always true)
Sr. Member
Dec 9, 2007
537 posts
I bought my place in 2004, luckily the builder didn't cheap out and use a loop for the phone/ cat 5e runs. 3 of the drops have 2 cat 5e cables so ethernet and phone is no problem but for the others I just have one cable so I used one of the 4 pairs for the phone and 2 of the remaining pairs for ethernet with a pair to spare. I bought some leviton punch blocks for the basement where all the wires meet which then go into my router. I have had no problems from the phone and ethernet being in the same cat 5 cable and I have been doing this almost 6 years.
Deal Addict
Mar 21, 2006
4403 posts
Burlington, Ontario
While it is odd that all the runs are done to the outside, it must have been done for either a structural reason (no route to unfinished space) or a lack of knowledge reason.

Regardless, it is done.

If you are looking to utilize a single cat5e cable as both telephone and 100mbit network, a professional installer may do it for you, but doubtful on warranting the performance of it.

What I would do is probably put a box outside big enough to hold a bunch of couplers.

Take the blue pairs out of all the cables and terminate them together for use as a telephone line.

You then need the green and orange to use for your network connections. Terminate them to RJ45s in the appropriate positions. Then plug them into a female/female coupler and use another cat5e cable to run into the house for each line.

Note: You will only get 100mbit network connections with this. Gigabit connections require all 4 pairs of wires in the cat5e cable.
Audio - Video - Data - Security - This is what I do
Deal Expert
User avatar
Dec 11, 2005
18772 posts
kitty wrote:
Dec 9th, 2009 1:24 pm
I believe that if you only wire it for 10/100MBps, one pair is left unused. That pair would be used to carry the telephone signal; whilst the remaining 4 pairs would be used for the network. So the phone and network signals would be on separate wires.
It doesn't matter if it is separate wires. Phone ring voltage is huge, much more than the normal signal. If you had phones and Ethernet running over twisted pairs in the same jacket, I would think it would be highly likely that whenever the phone rang you would have massive packet loss.

Why don't you just do it all ethernet and switch to a VOIP system for the house?

Or - just keep one phone jack, forget all the rest, and get an expandable handset cordless system. IE we only have one phone jack in the whole house we use, we just have 5 cordless handsets all hooked to one base.
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