There are a couple of ways. You can ask that callers identify themselves as they join the conference bridge. The name announcements will optionally be heard by all callers on the bridge line at the time, not just the conference call moderator. This setting is configurable on your line settings page, and thus can be configured differently for different lines in your account (if you have a multi-line setup.) To enable conference call service name announcement, check the box “Record & announce caller names”. If a caller doesn’t state their name, they’ll be badgered until they finally provide some utterance of identity.