The MASTER socket is the first socket where the line comes into the building. SLAVE sockets are for additional internal extensions.
Wandsworth shuttered telephone line jack outlets are designed to British Telecom standards and are suitable for connecting as follows:
- MASTER Master unit for connection as first socket to direct exchange lines and private branch exchange lines (PBX or PABX).
- SLAVE Secondary units as extension sockets for connecting on the same line and in parallel to master units.