This robust SIP speaker offers crystal clear HD audio functionality with a high-fidelity 8-Watt HD speaker. The GSC3505 supports Bluetooth devices, a built-in whitelist and blacklists to easily block unwanted calls, SIP and multicast paging, and integrated dual-band WiFi. By pairing the GSC3505 with other Grandstream devices, including desktop and cordless IP phones as well as the GDS series of Facility Access products, users can easily sculpt a state-of-the-art security and PA anno uncement solution. Thanks to its modern industrial design and rich features, the GSC3505 is the ideal SIP speaker for any setting.