4-Inch Multi-Touch Screen With 480 800 Resolution; Optimal Hd Audio, Full Duplex Technology; Yealink Noise Proof Technology; Built-In Rechargeable Lithium Battery; Up To 20 Hours Talk Time (In Ideal Conditions); Up To 75 Hours Standby Time In Wi-Fi Mode (In Ideal Conditions); 20-Foot (6-Meter) And 360 Degree Voice Pickup; Built-In 6-Microphone Array For Voice Pickup; 5-Way Conference Call; Hybrid Uc Meeting; Built-In Wi-Fi (2.4Ghz/5Ghz, 802.11A/B/G/N); Built-In Bluetooth 4.2.