We consider the problems of explaining and forecasting the penetration and the traffic in cellular mobile networks. To this end, we create two regression models, viz. one to predict the penetration from service charges and network effects and another one to predict the traffic from service charges and diffusion and adoption effects. The results of the models can also be combined to compute the likely evolutions of essential characteristics such as Minutes of Use (MoU), Average Revenue per User (ARPU) and total revenue. Applying the models to 26 markets throughout the world we show that they perform very well. Noting the significant qualitative differences between these markets, we conclude that the model has some universality in that the results are comparable for all of them.