Telephone cables carry the signal from the telephone company to your telephone. They run from the telegraph pole into your telephone interface box, which is typically located on your exterior wall. The telephone cable ends up in various places inside your house and is terminated by a connectivity device called an RJ-11 telephone jack. The RJ-11 jack is a common household jack or female receptacle that allows telephones to be connected to the telephone wires that run to the telephone company. It is quite easy to terminate a telephone cable with an RJ-11 jack once you learn the basic steps.
Turn off power to your telephone line by unplugging the telephone wire inside the telephone interface box located outside your house. The telephone interface box is typically found on the wall nearest to where the telephone line runs into your house from the telegraph pole.
Strip off one inch from the outer cover of the telephone cable with a cable stripper to expose the four inside wires. Strip off 1/2 inch from each inner wire with a wire stripper.
Open the RJ-11 telephone jack by removing the snap-on cover. Connect each colour-coded wire to the corresponding colour-coded terminal screws with a screwdriver. Typically, the cable consists of red and green wires, which make a pair, and yellow and black wires, which make another pair.
Replace the jack cover. Fasten the jack to the wall with the screw or double-sided tape that came with the jack. Replug the telephone wire in the telephone interface box outside the house.