embers and friends scattered around the globe, can gain by avoiding the normally sky-high charges associated with Chapter 9 IP Services international calling. Many analysts expect that sales of VoIP equipment will grow rapidly in the coming months and years. IPT Versus Internet Telephony Versus VolP People use several IP-related terms interchangeably. However, according to the Interna- tional Telecommunication Union (ITU; www.itu.int), there are distinctions between the following terms: IPT-The transmission of voice, fax, and related services over packet-switched IP-based networks. Internet telephony and VolP are specific subsets of IPT. Internet telephony-Telephony in which the principal transmission network is the public Internet. Internet telephony is commonly referred to as Voice over the Net, Internet phone, and net telephony, with appropriate modifications to refer to fax as well, such as Internet fax. VolP-IPT in which the principal transmission network or networks are private, managed IP-based networks. This chapter generally uses the encompassing term IPT. With leading telecommunications carriers and cable companies unveiling major VoIP initiatives, consumers and businesses will be hearing a great deal more about VoIP in the near future. Despite the long road ahead, consumer and business migration to VoIP is on the verge of moving out of the early adoption phase and into the mainstream, and the hope is that widespread (although not ubiquitous) VoIP use will finally take off by 2007. It appears that some 20% of businesses have already adopted VoIP technology. Interestingly, companies are citing benefits other than reduced costs as the reasons for switching to VoIP. The biggest reasons men- tioned have to do with strategic investments, integration with existing IP VPNs, employee mobility, and increased productivity. Reduced costs alone are not likely to propel IPT or VoIP to the pedestal envisioned by its proponents. The IPT Evolution We know that IPT is here for several reasons. First, we can do it effect