Telephone Wiring

Telephone wiring includes the wires over which signals are sent and the plug that allows a telephone to be attached. A telephone plug allows a telephone to connect to the local telephone network. It plugs into a socket or jack fixed to the wall or baseboard. The standard for telephone plugs varies from country to country, although the registered jack 11, or RJ11, has become by far the most common. Other types resembling the registered jack series, used for Ethernet connectors, cause confusion when users don’t know the difference. Such jacks are also seen on the bodies of phones.

Historically the telephone was often owned by the supplier and permanently wired in to the telephone line they supplied, but as phone markets became more deregulated there was a need for a simple plug-in interface that consumers could use. Many countries initially used their own connectors. For example, Bell System companies in the 1960s used a round plug about 40 mm in diameter with four prongs about 15 mm apart. National connectors remain in service, but few are used for new installations.

Sometimes the same connector is used by different countries but wired in different ways. For example, telephones in the United Kingdom typically use a cord with a BT style plug on one end and an  RJ 11 6P4C connected to the other, but this connector is often wired in the same way as the BT plug rather than according to the RJ11 standard.

Bell system line cord as used in the mid-1960s

Plugs Used in Different Countries and Territories

This list covers only single-line telephone plugs commonly used in homes and other small installations. Special telephone sets use a variety of special plugs, for example, micro-ribbon for key telephone systems and the wide array of registered jacks.

External Links

• Telephone plug list — at Steve Kropla's World Wide Phone Guide
• International telephone adaptors