Telecom For Dummies

The male loopback plug for a T-1 circuit consists of an RJ-45 connector with pin 1 connected to pin 4 and pin 2 connected to pin 5. You can easily make your own male loopback plug — or have your hardware vendor make one for you.

 Tip  The next time a technician from your hardware vendor is in your office, have the technician make a loopback plug and leave it hanging on a nail in your phone room. If the tech is feeling generous, he or she may even make both male and female loopback plugs.

Here’s what you need to make your own male loopback plug:

• RJ-45 connectors: You can buy packs of RJ-45 connectors from any electronics, hardware, or home improvement store for anywhere from $5 to $10.

• Crimping device: This tool enables you to secure the wires into the RJ-45 connector and costs between $20 and $55. Nicer crimping tools also allow you to work on RJ-11 connectors, which are used for standard telephones, fax machines, and analog modem lines.

• Wires: You use wires to input into the connector. You can cut them from any flat phone or modem cable. After you cut a 6-inch section of cable and remove 2 wires, you need to insert them into the RJ-45 connector (see Figure A-1).

  Figure A-1: The pin configuration for a male RJ-45 plug.

This configuration allows you to connect the transmit wires 1 and 2 to the receive wires 4 and 5. After inserting the wires into the slots, simply crimp down the copper blades in the connector to secure the wires and complete the connection. You now have a male loopback connector.