Model 40TB-IP Talk-Back Speaker enables two-way conversations via SIP and also allows for standard paging and background music via multicast. Use a hard wired button to initiate a SIP call, or use the optional wireless remote, Viking model BTR-3. The remote can also be used to adjust speaker volume. The 40TB-IP’s integrated microphone enables talk-back and also monitors room noise to automatically increase speaker volume when necessary. For more information visit www.VikingElectronics.com.