Patent ID: 7876744

Claim:
A method of providing a collect call service based on a voice over Internet Protocol (VoIP) system, the method comprising: establishing a first communication link between a called gateway and a collect call switch, on receiving a collect call request from a caller terminal via a VoIP network located between i) a calling gateway being coupled to the caller terminal and ii) the called gateway being coupled to the collect call switch, wherein the caller terminal can access the called gateway by use of already-known access information; establishing a second communication link between the collect call switch and the called terminal; temporarily transmitting voice of a caller to the called terminal to identify the caller when the second communication link is established, and then prohibiting voice transmission until a collect call acceptance arrives after the temporary voice transmission; connecting the first communication link and the second communication link to initiate a billing process for the second communication link responsive to the collect call acceptance in the form of a dual tone multi-frequency (DTMF) signal from the called terminal; and releasing the connected links to end the billing process responsive to a normal call end request from one of the caller terminal and the called terminal.