Innovative audio scheduling, paging, emergency notification, and school bell system that is used by hundreds of schools, factories, and businesses. BellCommander's audio scheduler is ideal for factory and school bells with support for unlimited day schedules, multiple zones, and over 200 events per day. Audio can be played through the PC's sound card, to networked PC's with the BellCommander client installed, and to network audio players. Bells, sirens, lights, and intercoms with contact closures can also be controlled using external relay controllers. The external relay controller acts as a flexible and easy-to-use alternative to traditional electronic and mechanical timers. In addition, BellCommander can send bells over traditional PBX phone systems and modern IP phone systems that support SIP. BellCommander can also be used as a paging and emergency notification system. Using a standard IP network, pages can be sent to networked PCs and to network audio players. Pages can be targeted to individual PCs or network audio players, to groups of clients, or to the entire system. Pages may be pre-recorded or broadcasted live from a PC microphone or SIP phone.