To reduce the invalid hold of network resources by shortening the response time.

When a communication apparatus 4 calls a communication terminal 1 to inform that there is an incoming call; the communication apparatus 4 measures and records the response time as a time between transmission of a calling signal to the communication terminal 1 and reception of a response signal indicating that the communication terminal 1 responds, and transmits the response time to a charging apparatus 6 together with communication charge information including a transmission communication terminal number, an incoming call communication terminal number, and a communication time after the communication is completed. The charge apparatus 6 records the received response time together with the communication information into a recording apparatus via a communication apparatus 5, and discounts a part of the communication charge to be charged to the communication terminal 1, depending on the length of the response time totalized for each communication terminal.