The proposed approach to determination of tariffs for telecommunication services allows to take into account nature and specific characteristics of each services and conditions of providing, in contrast to existing. The core of the proposed approach is the model of services providing process (conceptual model) that takes into account only elements of the existing network, that involved in realization of provided services, and simulation model which determines operational costs through modeling work of a similar scale hypothetical subsystem using the original data corresponding to the current state of the market and the current legislation, and taking into account particular qualities of the operator (provider). It allows to refuse of using the separate accounting system, as well as to eliminate the disadvantages of the "historical" costs method and Long-Run Average Cost method, which can significantly reduce the complexity of the tariffs determination procedure and increase their validity. Its usage gives the greatest effect in the case of tariffs determination for telecommunication services, in conditions when the operator provides a wide range of services, as well as in calculation of tariffs for new services. The proposed approach of determination of tariffs for telecommunication services are successfully implemented in practice activities of some telecommunications operators.