Hack your House: Run both ethernet and phone over existing Cat-5 cable

Step 9: Select proper wires

You need to figure out which wire in the phone cable is red and which is green. Mine were both physically colored black. To figure this out, you can find a phone cable that does have colored wires and use it for reference (you can see the colors sticking into the clear jacks.) You can also search online or use the picture provided here.