Hi

Ive got a job comming up where I need to stick in a ext page setup in a warehouse.

Whats the easiest way of doing this do I need to get a PA AMP & Speaker or can i get some kind of self powered purpose built horn speaker that plugs directly into the ext page port.

Valcom makes self amplified speakers and horns. You just need to get a power supply rated for the ammount of speakers/horns and wire the 600 OHM paging output of the system to the Tip and ring of the speakers.