How to Install T1 Lines

by Richard Asmus
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A T1 line carries 1.544 megabits of information between two points in both directions. Uses for T1 include telephone lines, video transmission and computer interconnections. The use of a particular T1 line depends entirely on the traffic exchanged between the two terminals. T1 lines run over copper cable, microwave radio and fiber-optic cable. Consumers and small businesses lease T1 lines from telephone companies. Large companies build transmission systems that carry multiple T1 lines. To install a T1 line you must first establish end-to-end continuity and know electronic installation procedures for the cable for your particular system.

Step 1

Order a T1 line from your telephone company. The company will install an interconnect terminal to which you must connect your equipment. The connection point may be an RJ-45, which is like a standard plastic telephone receptacle, but wider with more wires. But it may be different, depending on the telephone company and your application.

Step 2

Install a connector on both ends of a cable to connect the T1 line to your equipment. The cable must have at least four wires. Two of the wires connect the signal coming from the opposite end to the terminal at your end. The other two carry the signal from your equipment to the opposite end. The plugs on the ends must be compatible with both the telephone company receptacle and your equipment. The cable may require crimping or soldering. Depending on your application, you may need to do this at both ends of the T1 line.

Plug the connectors into the telephone company receptacles and your equipment at one or both ends of your system, depending on your application. Turn on the equipment. If the T1 line and your equipment work, your T1 line is successfully installed.


  • For long runs of cable between your telephone company interconnect point and your equipment, use shielded cable to prevent interference on your T1 line.


  • For short distances, shop for a ready-made cable to install your T1 line. Consult your telephone company or the manufacturer of your equipment.
  • If your T1 line doesn't work, loop your system back on itself at both ends. Your loopback should be at the ends of the cables, at the last point before they touch the equipment installed by the telephone company. If both terminals work, the T1 interconnection is bad and only the telephone company or the service provider can fix it.
  • The RJ-45 connector carries a single T1 line. For multiple lines, use more RJ-45s if they go to different locations. But for a single location, use DB-sub 9 or DB-25.


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About the Author

Richard Asmus was a writer and producer of television commercials in Phoenix, Arizona, and now is retired in Peru. After founding a small telecommunications engineering corporation and visiting 37 countries, Asmus studied broadcasting at Arizona State University and earned his Master of Fine Arts at Brooklyn College in New York.

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