How many audible devices will the OSI Alarm System accept?

 You can have one hard wired siren. In addition the system allows you to add multiple wireless sirens, but keep in mind that the system can handle a total of 100 wireless devices including wireless sirens, door/window sensors, motion pir sensors, and remote controls. We tested 1 hardwired siren with 5 wireless sirens connected to the same system in a 3000 square ft building and it worked perfectly fine.