Abstract: In a telephone network, an incoming call is once received using an automatic voice response. A ring tone is not played immediately after the incoming. In the automatic response, an authorization sound that is necessary every time connection to the caller is made is generated each time by superimposing a background sound on a random number generated through random number generation processing. The caller is notified of the authorization sound. A ring tone is played in response to only incoming calls that return a valid response value, and not played in response to incoming calls that return an invalid response value.

Abstract: In a telephone network, an incoming call is once received using an automatic voice response. A ring tone is not played immediately after the incoming. In the automatic response, an authorization sound that is necessary every time connection to the caller is made is generated each time by superimposing a background sound on a random number generated through random number generation processing. The caller is notified of the authorization sound. A ring tone is played in response to only incoming calls that return a valid response value, and not played in response to incoming calls that return an invalid response value.