The estimate of the parameters of discrete probability distributions class (a,b) (Klugman et al. 2004, Escalante 2006) is presented in detail by methods of moments and maximum likelihood studied. A general algorithm is proposed to generate random numbers of distributions class (a,b). The results are presented so it can be implemented in any suitable programming language. Examples were made in R with real data taken from different disciplines.Keywords: Random models of frequency, estimation of distribution class (a,b), risk theory, the collective risk model, Panjer’s algorithm.