Using group listen allows callers to be heard through the phone's handsfree speaker but to only hear the phone's handset microphone. When group listen is enabled, it modifies the handsfree functionality of the user’s phone in the following manner
When the user’s phone is placed in handsfree/speaker mode, the speech path from the connected party is broadcast on the phone speaker but the phone's base microphone is disabled.
The connected party can only hear speech delivered through the phone's handset microphone.
Group listen is not supported for IP phones or when using a phone's HEADSET button.
For T-Series and M- Series phones, this option can be turned on or off during a call. For other phones, currently connected calls are not affected by changes to this setting, instead group listen must be selected before the call is connected.
Group listen is automatically turned off when the call is ended.