Lock Your Conference. Once everyone's arrived, shut the door and lock it. Lock your conference call against further arrivals. If everyone's there, then start without further interruptions. And it's also a great way to insure prompt attendance… It's a feature that's standard on most of our conference call services. You lock your call using the dialpad on your telephone. NOTE: Once a guest leaves a locked conference call…they can't return. NOTE #2: An operator can't join your call, either, if there's a problem caller.