The SpeakerPhoneMute and SpeakerPhoneUnMute entries define the AT commands that mute and unmute the speakerphone.
One or more command strings.
HKR, SpeakerPhoneMute, 1,, "at#spk=0,,,<cr>" HKR, SpeakerPhoneUnMute, 1,, "at#spk=1,,,<cr>"
These commands are issued after a call has been connected in voice mode and the speakerphone has been enabled. These commands are sent only after the speakerphone has been enabled and the TAPI function phoneSetHookSwitch is called to change the mute setting.