You do not need to be an electrical expert to add extra telephones or telephone lines to your already installed network interface device. Once you have one telephone installed, usually done by the company when you begin to use their service, it can be a steep cost to wire in another telephone. Skip the extra cost and do it yourself!
The standard telephone wiring way of using green, red, black, and yellow is becoming obsolete, and if you are using Cat 5 cable, there is a new wiring system. It goes as below.
T1- White with blue marks
R1- Blue with white marks
T2- White with orange marks
R2- Orange with white marks
Only two of these wires are needed for a phone line, which means that normally there are two extra lines. These two extra lines do not give you a new location for the same phone number. They actually have a completely different phone number. This can work well if you are installing a fax machine or a modem for internet as you will not want it to be connected to your phone number. If you are using a phone that was created to have more than one line, you are done by simply connect your phone to the wires. If your phone is not adapted to have more than one line, you will need to take an extra step to add a connection point for your second phone.
Changing Your Wires
The easiest way to add in a line two is to add a new jack right beside the line one jack. In this way, you can have the two lines right beside each other, and you will not lose a line one jack (this is what to happen were you to rewire that jack). In this case, you would simply buy some wire and use the extra wire to extend the wires for the line two. This way your wires for the line one jack will still be attached to the original hole, and the line two jack will now have the new wires connecting it with the new jack.
If you have done the wiring correctly, and your phones are still not working, you may need to call the local phone company and make sure that the problem is not on their end. Before you do that, try different phones or fax machines in the slot to make sure that the problem is not based on your machine's malfunctioning.