In Parts I and II of this paper a generalized analytical queueing methodology for studying the performance of radio nets was presented and the methodology was applied to a number of net systems. In this part the methodology is refined and its assumptions and definitions are validated. It is important to emphasize that several of the refinements introduced here alter the methodology for multiplefrequency systems that was introduced in Part I; specifically, the distribution of queued messages among the stations and the state transition probabilities are refined. In addition, the grade of service is redefined, the waiting time distribution is introduced, the methodology is extended to use Erlangian statistics, and the ranges of the parameters

, and ρ are specified for which the model is applicable. Also, the model\´s performance predictions are validated by comparison with a computer simulation.