The GSC3506 is a 1-way public address SIP speaker that allows offices, schools, hospitals, apartments and more to build powerful public address announcement solutions that expand security and communication. This robust SIP speaker offers crystal clear HD audio functionality with a high-fidelity 30-Watt HD speaker. The GSC3506 support built-in whitelists ,blacklists and greylists to easily block unwanted calls, SIP and multicast paging, group paging and PTT. users can easily sculpt a state-of-the-art security and PA announcement solution. Thanks to its modern industrial design and rich features, the GSC3506 is the ideal SIP speaker for any setting.