Network IP Tools
Use the following tool for estimating the bandwidth needed for handling a given number of VoIP calls through the network or determining the number of calls we can make at a given bandwidth.
http://www.erlang.com/calculator/lipb/
Use the following tool for estimating the bandwidth required for making calls at peak hours, this calculator is based on the Erlang B traffic model.
http://www.erlang.com/calculator/eipb/