This paper proposes and investigates a service model of the voice traffic in multiprotocol label switching networks. The study of Multiprotocol label switching networks (MPLS) requires a formal description of processes occurring in them, development of mathematical models, reflecting main properties of the investigated object and allows calculating the values in the required operating mode. In this paper, we develop the model of functioning MPLS network in the form of a multi-phase, multi-channel, open-loop system. We propose analytical expressions describing the process of mutual influence when servicing requests of various communication directions. To determine parameters of quality of service quality and bandwidth channels MPLS network, necessary compare them with the values of normed and assess the compliance of the specified standards.