Charging Function

The mechanism of calculating and recording the charge on each call based on the tariff system is referred to as a charging system. The switching system automatically records the frequency of communication, origination dates, communication times, and called parties. Based on these data, the system obtains communications charges by computer processing.
Each exchange therefore has data in memory for all information required for charging, such as the time available for communication per unit charge depending on the communication distance.

The following procedure outlines charging processing by the exchange:

1. When the terminal terminating a call responds to it, the exchange on the originating side writes the current time to memory.
2. Upon completion of the call, the exchange calculates the call time from the difference between the response time and the call end time. It divides the result by the unit time depending on the communication distance to obtain the measured rate.
3. The exchange reads the charge meter of the originating terminal from memory, adds the obtained measured rate, and writes the result back to memory.