TNG assumes that the free minutes will not be exceeded. We then use the
rate supplied to us by the service providers that they charge per second or
per minute based on the fixed cost of the package.
For example: if a package cost you R1000 and you get 1000 minutes with that
the service provider will give us a per second cost of 1.6666667 cents and
we will always charge calls at this rate. It is up to the client, or his
premicell provider, to ensure that they have enough premicells as to not
exceed their free minutes, thus giving them the optimal savings.