Understanding and Utilizing RJ11

RJ11 stands for “registered jack” and was originally designed by phone companies in the 70’s and is used for analog voice lines. It is a single pair jack, a jack with 2 wires. It is typical to find RJ11s with 6 positions, which are the metallic pins on the underside of a phone jack. To make a RJ11 a mod plug, crimper, and cable is needed. Slide one pair, two wires, into the mod plug so that they line up with the two center pins which are the first position. Place the mod plug with the cable in it into a crimper and close it down on the mod plug. This will cause the pins that were previously slightly raised to crimp down on the wire, cutting through the wire housing and creating a connection.

When cabling a voice line it is wise to cable with only RJ45 jacks. RJ11 jacks only take Rj11 plugs, however a RJ45 jack can take a RJ11 or RJ45. This will be useful if in the future a computer line or VoIP (voice over IP) which is cable on a RJ45 plug, if you had a RJ11 jack in that place re-cabling the entire run would be necessary to accommodate VoIP. When punching down an analog voice line on an RJ45 jack only punch down the blue pair, take the remaining three pairs and wrap them back around the housing of the cable. If and when it is decided to upgrade that jack to a data line or VoIP the three cables that were saved can then be punched down to create a data line. Also, if in the future another line is required in the same location the three pairs wrapped around the housing can be useful again. Take the orange pair and punch them down on a separate jack on the blue pair location just like the first. You can continue this process with one cat5e or cat6 cable to have up to four lines off of the same cable.