It comprises of integration of plant telephone system with PA system.

The telephone system provides voice communications between offices & operational buildings of the plant through intercoms and provides access to outside trunk lines.

PA system provides transmission of routine voice messages over loudspeakers, to all or selected areas of the plant, in a reliable, safe and efficient manner.

On integration of the two, the PABX user gets access to the PA system where by they can announce over the loudspeakers from their telephones. The telephone user can announce in individual zone OR in multiple zones OR in all zones.