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 allows the user by entering a 5-digit number to receive a call from any concrete company’s telephone. There are no definite groups for picking up the call. One can pick up the call from any telephone set; it is only necessary to enter the required code and the extension number of the phone, which has to be picked up.