Rate change notification

In a cellular mobile telecommunications system, apparatus and a method for altering the charge for a call if the occupancy of radio channels is above or below an appropriate threshold. For one proposed service, the users are charged less if they make calls during the time when the occupancy of radio channels is less than a threshold. For users having another proposed service, the charge is greater when the occupancy of the radio channels is above another threshold. Advantageously, users are encouraged to use the mobile telecommunications service when the occupancy of regular channels is low, and to use the service less when the occupancy of the radio channels is high.