Cumulative operational timers and methods for cellular telephones

Cumulative timers are used in a cellular telephone to record total mobile "ON" time and total transmitter "ON" time. These "ON" times are periodically stored in long term nonvolatile memory. The period is chosen such that a time-limited number of write cycles of the nonvolatile memory are not exceeded over the life of the dual mode subscriber unit. As a consequence of utilizing periodic updates, rather than power-up event driven updates, solves this problem of the limited lifetimes of the nonvolatile memory device is solved. The use of the cumulative timers and its related computational method in a mobile telephone permits factory personnel to calculate actual mean time between failure data based upon customer returns. Timer information provided by the cumulative timers and computational method may also be used to indicate warranty fraud.