Telephone wiring is typically crimped into a connector plug such as the modular plug at the end of a telephone cord. The connector itself is set into a crimping tool and the wires inserted get a crimp connection to the plug. The crimp bites into the insulation around these tiny wires, so the wires do not have to be stripped.
Slice the outer jacket of a phone cable lengthwise with a utility knife. Be careful not to cut the inner wires as you make a 2-inch slit in the jacket. Pull the individual phone wires through the slit and cut away the empty two inches of jacket.
Hold a modular plug in one hand with the spring clip on the bottom and the front of the plug facing away from you. Number the holes in the back of the plug with number one being on the far left, and number four on the far right.
Push the proper wire colours into the correct slots. The wire colours will depend on whether you have a newer or older telephone cord. Insert the black wire, or the white wire with orange stripes into hole number one. Put the red wire, or the blue wire with white stripes into hole two. Place the green wire, or the white wire with blue stripes in hole three. Put the yellow wire, or the orange wire with white stripes into hole four. Push each wire into its hole as far as it goes for best connection.
Place the modular plug into the jaws of a crimping tool. Be sure none of the wires from the telephone cord fall out of the plug. Squeeze the handles of the crimper forcefully to make a solid crimp on the connector. Hold the plug in one hand and pull on the attached cord to check for a firm crimp.
Double-check the telephone wiring for proper colour order in the connector before applying the crimp. Once the plug is crimped there is no way to change the wiring order.