Poly Calisto P240 M Wired Handset Model_Chromebook 11 New Smart Fan 5 Software New Smart Fan 5 Software Blackview BV4800 Rugged 6 800 Hz when used with a compatible communications application Control Function Green Call Button Answers an incoming call or places a supported outgoing call Red End Button Ends or rejects a call and clears an entered number 12 Key Dial Pad Enters telephone numbers and supported DTMF commands Speakerphone Button Transfers audio between the handset earpiece and built in speakerphone Volume Buttons Adjust incoming call volume Function Keys Select context sensitive options shown on the LCD Navigation Control Scrolls through menu options and adjusts settings Mute Function Mutes or unmutes the microphone during a supported call Technical Specifications: