Snom VoIP Conference Phone with 3 SIP identities Full-duplex speaker The built in batteries on the 2x detachable microphones can run continuously for up to 12 hours without recharging or up to 70 hours in standby mode Bluetooth and DECT technology also allow compatible devices as well as smartphones to be connected The Snom C520 grows to meet your demands: Even the largest conference rooms can be connected to the base station with the addition of up to three optional C52 wireless speaker units for a significant increase in range