PA systems with many speakers are widely used to make announcements in public, institutional and commercial buildings and locations. Intercom systems, installed in many buildings, have microphones in many rooms allowing the occupants to respond to announcements.

Specialized PA systems are available such as PA over IP (Ethernet), Long line public address system and Large Venue systems.
Depending on the application,each system can cater to simple to complex PA systems each with varying functionality depending on the application.