It is a call which is made over internet protocol (VoIP). For example,
one can call using Google Voice to other recipient located miles away. Such
call can also be international.
Integration of the phone set (cell or land line) into the company phone system. For instance, if it is impossible to find a person by the office phone, then with the help of the integrated cell phone one can set a call redirection to a cell or another telephone number, in case if that telephone is also unavailable the call will be redirected to a voice mail.