How does it work?
From VoiceMailTel Wiki
VoiceMailTel provides you with a Toll Free number, 1 Moderator PIN, 1 Users PIN and 1 Listeners PIN.
All participants dial the Conference Toll Free number. Until the Moderator joins the call all participants are on hold, listening to default music. When the Moderator joins the Conference Call begins and when the Moderator ends the call all participants are placed on hold again.