To compute a call charge every telephone number called by each portable telephone, sum up the computed charges and store the result.

In a mobile communication system, portable telephones 1-1, 1-n receive their own charging signals from a base station controller 3 via control channels during calling. Each has a counter for counting the number of reception times and functions for multiplying a basic call rate by the count of the counter to obtain a call charge by the call after ending the call, summing up the call charges every called telephone number, and storing the result.