View Unidentified Callers (Web App)
If an organizer provides phone numbers for their meeting, then anyone who dials in to the audio conference using a telephone but doesn't enter an Audio PIN is known as an "unidentified caller". This means that GoToMeeting doesn't have any way to identify them by name, so it views them as a separate participant.
Organizers will see those individuals appear in the Attendee list as "Caller [X]".
Mute unidentified callers
You can mute the caller just like you would with any other attendee.
1. Click the Arrow icon next to their name.
2. Select Mute <caller>.
3. To unmute the caller, select the arrow again and click Unmute <caller>.