Rondee is smart about handling timezone issues. All Rondees are scheduled in the timezone of the organizer. How do we know the correct timezone for your conference call? We know it because to schedule a Rondee you must be logged in as an organizer (either initially or by the time you complete the process) and part of the registration process involves telling Rondee your timezone.
All of your invitees are informed that the conference call will be occurring at the time you specified and with respect to the timezone you have registered. So if you registered with EST as your zone, your attendees for the teleconference will see the time reported in EST