Controlling indicator associated with telephone appts.

摘要

The time difference between two tariff pulses is determined from the dialled telephone number and stored data for day type and day time dependent tariff zones. Alternatively it can be determined by measuring the time from realising a call connection up to the appearance of the next metering pulse.The timed display up to the metering pulse appearance may be changed in time intervals. The latter duration may be selected in dependence on the time difference between two metering pulses. The time duration of the intervals is typically reduced up to the appearance of the next metering pulse with the reduced time.