|Integration of the voice and the data in a same netork is not a novel since in the last decades have arisen solutions from different manufacturers and oprators, having allowed the use of network WAN of data of the companies (typically connections point to point ans frame reay) for the transmissin of the voice traffic. Nevertheless, the lack of stadards, as well as the long term of amortizaion of this type of solutions has not allowed a wide implantation of thes ones. In tis article, an analysis of the telephony of Telecommunications to determine the reuirements in the convergence of telephony IP as an alternative a opposed to the network of traditional voice. In order to achieve this an evaluating model is developed in three stage Sizing and design the network of Telephony in a arameter way. Analysis of Telephony IP considering different platforms, with the economic evaluation of the alternativa, and finally, determinationof the operative viability of the area of Privte Telephony.