Core Features: W70B: Up To 20 Simultaneous Calls Up To 10 Dect Cordless Handsets Up To 10 Sip Accounts Support Opus Audio Codec Noise Reduction System Tls And Srtp Security Encryption No Perception Upgrade Cp935W: 4-Inch Multi-Touch Screen With 480 800 Resolution Optima Hd Voice, Full Duplex Technology Yealink Noise Proof Technology Built-In Bluetooth 4.2 Built-In Wi-Fi (2.4Ghz/5Ghz, 802.11A/B/G/N) Wi-Fi And Dect Mode Switchable (Switch Via One-Touch) Built-In Battery Up To 20-Hour Talk Time (In Ideal Conditions) Up To 167-Hour Standby Time In Dect Mode (In Ideal Conditions) 4 Hours Charging Time 20-Foot (6-Meter) And 360-Degree Microphone Pickup Range Built-In 6-Microphone Array For Voice Pickup 5-Way Conference Call Support To Connect With A Bluetooth Expansion Microphone Cpw25 Hybrid Uc Meeting