Bandwidth calculation for VoIP networks based on PSTN statistical model

Abstract

This paper shows an analysis how to calculate proper bandwidth for VoIP calls after proper dimensioning of PSTN network. For this purpose, we use Erlang B and extended Erlang B formulae. Further, we have developed a software tool, named Bandwidth Calculator to calculate proper number of the circuits on the PSTN side and after that IP bandwidth. Traffic analysis is conducted for VoIP networks considering impact of many factors on the bandwidth such as: voice codecs, samples, VAD, RTP compression. The results obtained by bandwidth calculator are compared to simulation results and data obtained by measurements.