Yearning to figure out exactly what the impact of a new Voice over Internet Protocol (VoIP) network would be in terms of bandwidth and cost? Then you might want to bookmark this link [1] that provides several different calculator tools for  estimating the bandwidth required through an IP-based network for a fixed number of voice paths. There's also a neat "minutes and lines" calculator tool for approximating the number of voice paths that should be created through a wide area network if you have an idea of the number of minutes of calls which the interconnected switches would generate on a daily basis. There are also several other free and low-cost calculator applications on the site [2].