The Valcom approach with powered speakers; four wire connections to each speaker.
Paging staff members in the office,  in open spaces, and separate area call ed zones. Add a feature to have speaker become two way; page from and answer back directly to the speaker.
Bogen Centralized Paging to 250 WATTS
Select the Valcom Paging System with distributed power for multiple
site applications.
Select Bogen Paging System for single site applications for a centralized amplifier with easy installation with a single connection from speaker to speaker..
The Page Control allows the configuration of paging features such as paging to spefic areas called "Zones" or all Zones, and allows the number of speakers to be connected in the Paging System
The array of speakers include from left to right:
horn,with up to 1/4 mile range for large open areas; square of rectangle ceiling drop in, looks like a ceiling tile; and round speakers both used in the office environment with dropped ceilings. Four wire connection from speaker to speaker.
The Bogen with non-powered speakers; two wire connections to each speaker.