British Telephone Sockets - Connector On Phone

Connector On Phone

The connector on the phone is not standardized: the connector at the wall is standardized by regulation, to allow individuals to use their own phones (interconnection), but the wire from the phone to the wall may be hard-wired to the phone, or use various connectors.

Typically it will have a 6P4C or 6P2C modular connector at the telephone end: this latter may be wired as per the RJ11 standard (with pins 3 and 4), or it may be wired with pins 2 and 5, as a straight through cable from the BT plug (which uses pins 2 and 5 for the line, unlike RJ11, which uses pins 3 and 4). Thus cables are not in general compatible between different phones, as the phone base may have a socket with pins 2 and 5 (requiring a straight through cable), or have an RJ11 socket (requiring a crossover cable).