tap into a cat 5 phone line


macrumors newbie
Original poster
Jun 1, 2006
i'm 'helping' run a phone line to a new room at a friends house.
they have voip - don't know the company- so no phone
connector box. there is a phone line running near the room
that i can tap into, but it is cat 5. how do i find which
two lines of the 8 are the phone lines?
thank you.


Moderator emeritus
Mar 16, 2004
Andover, MA
You'll need to find either end of it to be sure. No matter what might supposed to be the 2 or 4 wires to be used, you don't know until you look at the end(s).

Are you sure you can't run another wire? It's a much better thing to do in the long run, esp. if they ever want to use the line for ethernet in the future.


macrumors 65816
Aug 30, 2003
Snellville, GA
It depends entirely on the installer, which is why you chould be glad there's only... 28 combinations of 2 wires with 8 choices...

Honestly, it shouldn't be that hard.

Try color + color/white combinations first.

As hmmfe says below, blue is usually used first.


macrumors regular
Feb 28, 2003
Well, it could be any of the 4 pairs as jsw says. But to give you something to go on, I'd try the blue/white, blue pair first. Then try the orange/white, orange pair. If the wiring is to standard, the blue pair is line 1 and the orange pair is line 2.