The function is available in some telephone networks and it allows
receiving the other call at the moment of the actual conversation by the method
of setting the active call in the waiting mode or cancellation. This will let
not to miss an important call and to agree upon time when it will be possible
to call back.
IDC projected over 9 billion minutes of voice traffic to travel over worldwide packet networks in 2000, exceeding 135 billion minutes in 2004. Service revenue is projected at 1.6 billion in 2000 and 18.7 billion in 2004.