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 service for determining from which number a client has called. This helps to decide how to answer on the incoming call. A telephone company sends DNIS number to the telephone client’s system during establishing connection. As a rule, DNIS number consists from 4 to 10 digits.