off-premise extension


Also found in: Acronyms.

off-premise extension

A telephone in a remote location that is treated as an ordinary extension phone. Before IP telephony was developed, off-premise extensions (OPXs) were handled by forcing the PBX to complete an outbound circuit in addition to the inbound one.
References in periodicals archive ?
This permits off-premise extensions (OPX) and enables users to terminate Direct Inward Dial (DID) circuits into their PBX or key systems.