There s a widely held misconception that telephone wiring is impossible for those who aren't telecommunications professionals. That, of course, is what the local phone companies would like customers to think. If you can figure out how to wire speakers for your new stereo, you can easily wire your home or small office for your new phone system. The basics of the wiring is pretty easy to understand.
Most telephone wires are one or more twisted pairs of copper wire.
This consists of a red and green, which make a pair, and the yellow and black wires, which make the second pair. One telephone line only needs two wires. Therefore it follows that a four strand wire can carry two separate phone lines, and the twisting keeps the lines from interfering with each other. If you need to run more lines than that, you may want to use a six strand or higher wire. Telephone wire comes in two gauges - 22 and 24 gauge.