First of all, you need to call your phone company and inform them about your interest in installing a second phone line. You will be informed with the services that you will get with your new line. Here, if you are planning to use the line for fax purposes, then you should try to stick with the basic plan, in order to save your money. Inform the company representative that you just need a technician to activate the phone line. You can do all the remaining work inside your home yourself. Once the order is complete, you will be given the new phone number and a date as to when the line will be active.
While you are waiting for the activation date, take this time to decide which phone jack is going to be the one to have the second line. Is it going to be the phone jack in the office? Is your teenager getting the new line in his or her room?
This is also a good time to get all of your other phone jacks prepared for the activation of the second line. This is important because if both lines are connected to one phone jack, it could hurt your phone quality.
Go to one of the phone jacks in your home that will keep the original number. Remove the jack from the wall by unscrewing the two screws securing the plate to the wall box. Gently pull the jack out of the wall.
On the back of the phone jack you will see four wires connected to the jack. The wires are typically green, red, black and yellow. Line one, or your home's original phone line is delivered through the green and red wires. Disconnect the yellow and black wires, cut the exposed wire with the wire strippers and wrap the two wires down the length of the phone line away from the jack. You can wrap the wire with electrical tape to secure it.
Before you put everything back together, plug your phone into the jack and make sure that you have a dial tone. If you do, then put everything back together and follow the above steps for each phone jack that you want to keep the original phone number. If you have no dial tone, reconnect the black and yellow wires, disconnect the red and green wires and check for a dial tone again. One set or the other will be carrying the original phone service.
On the phone jack that you determined is going to be for the second line, you will want to disconnect the red and green wires (if they are the ones that are currently delivering service) and leave the black and yellow wires connected.
On the date that the second phone line is to be activated, once the technician leaves, you should be able to pick up the handset and hear a dial tone. Now you have the phone flexibility to do what you want. If you ever want or need to change any other phone jacks over to the secondary line, just follow these directions and you will be all set!