Abstract: A method of calculating the maximum talk time by: a. determining rate for the period of time when the call begins b. calculating (i) the maximum number of time units remaining in the time period (ii) the maximum number of units before reaching system maximum talk time (iii) the maximum units before available funds exhausted c. using the minimum calculation of b(i), b(ii), and b(iii) as the talk time available and subtracting the amount from a copy of the PPCard balance d. if b(i) is the minimum, successively repeating the above steps for the next time period and adding the amount to the talk time.