Structured cabling

These standards define how to lay the cabling in various topologies in order to meet the needs of the customer, typically using a central patch panel (which is often mounted in a 19-inch rack), from where each modular connection can be used as needed.

Voice patches to PBXs in most countries require an adapter at the remote end to translate the configuration on 8P8C modular connectors into the local standard telephone wall socket.

In North America no adapter is needed for certain uses: With ports wired in the preferred standard T568A pattern, for the 6P2C plugs most commonly used for single-line phone equipment (e.g. with RJ11), and 6P4C plugs used for two-line phones without power (e.g. with RJ14) and single-line phones with power (again RJ11), telephone connections are physically and electrically compatible with the larger 8P8C socket, but with ports wired as T568B, which is common but often in violation of the standard, only the first pair, i.e. line 1, works.

In the United Kingdom, an adapter must be present at the remote end as the 6-pin BT socket is physically incompatible with 8P8C.

Regardless of copper cable type (Cat 5e/6/6A), the maximum distance is 90 m for the permanent link installation, plus an allowance for a combined 10 m of patch cords at the ends.