I have a small business. When the owner installed the telephone lines he installed 2 of them. We took the plate off and looked at the wiring within jack and he put 2 strands to each of the 2 jacks. We currently have 2 incoming lines with a 2 line telephone. This works okay.

However, we are now trying to expand to 4 line telephone. The instructions say to install a 2 two-line adapter onto jack #1 then connect the wiring to line #1 jack and into the back of the phone labeled l1/l2 then to take a jumper line from the other jack in the two-line adapter and into jack #2. This does not work.

Is it because there should be 4 strands into each of the jacks? How do we do this?

Thank you. Carol

What's on the back of the phone?

Normally a 2 line phone jack is wired as an RJ14. This means that the red and green wires of line 1 go to the red and green wires of the jack. And the red and green wires of line 2 go the black and yellow wires of the jack. This makes the jack and RJ14 and able to function with a 2 line phone. For a 4 line phone you may need to wire 4 jacks and then connect a phone cord from each jack into the phone. It depends on what the jacks are like on the phone.

It might help if you listed the exact make and model of the phone so we can research it.

Each phone line requires two wires. You can use a 4 wire jack and 4 wire cable between the jack and phone to provide the phone with two phone lines. Usually the red and green are the first line and the yellow and black are the second line.