Advanced - Behavior (Tab) - Phone Behavior (Section):
: Settings/intercom connect type/en
If the Alert-Info header is taken into account in order to allow auto answering behaviour like intercom, this option can be used to specify whether the phone answers in handset, headset, or hands-free mode, as well as the currently active audio device. Also, see Auto Connect Type. Please see also the new setting (starting V 10.1.74.0) call_info_audio_device for handling Call-Info information separatly.