Method and device for updating a prepaid balance

A mobile communication device, comprising:

• a transceiver;
• a controller configured to control operations of the mobile communication device and coupled to the transceiver and a plurality of modules;
• a storing module configured to store in memory a stored prepaid balance;
• an initiating module configured to initiate a wireless communication so that the device will enter active mode;
• a querying module configured to transmit, during the active mode wireless communication, a balance query to a service provider;
• a reception module configured to receive, during the active mode wireless communication, a response to the balance query;
• a response processing module configured to process the response to the balance query to obtain a new prepaid balance;
• a timing module configured to start a call timer to generate a duration value;
• and
• a tariff calculation module configured to calculate a tariff value based upon the difference between the new prepaid balance and the stored prepaid balance and upon the duration value.