It is the business practice of sending all clients' billing info to a separate company, who then does everything for you. It also allows a company to cut down on time and human resources spent on administrative tasks.
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.