Telephone cords are one of the more basic types of cables. Phone cables have remained mostly the same over the years with a few small changes here and there. There is a little terminology to know that will tell you a bit more about your phone lines, such as how they are wired and what type of plastic connector is on the end of the cable.

Phone cords come in two varieties, flat cords used to connect phones to the wall and coiled cords used for handset receivers. Flat cords will use either an RJ11 or RJ12 connector. These two connectors are the same size and look the same on the outside. On the inside, RJ11 will have four metal contacts for the internal wires inside the cable while RJ12 has six contacts. Since they are the same size, RJ12 is backwards compatible with RJ11. However, since RJ11 is the older of the two it is not compatible with RJ12.

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