 users. The definition we use for enterprise is a large-scale deployment of more than 500 phones controlled by a single large-dial plan, with features above and beyond the current TDM-based telephony that can be used only within the enterprise. Using this definition, enterprise phones were 100 percent TDM-based just more than 15 years ago. During a 10-year period from 1996 to 2006, the trend to IP Phones resulted in the tip- ping point of phones deployed transitioning from 100 percent TDM to more than 14 SIP Trunking 50 percent being IP-based. The trend for new phone deployments (see Figure 2-3) is now that more than 90 percent of new enterprise phone deployments use IP Phones. This trend from 1996 to 2006 was based upon the greatest value in the company occurring at the transition point of the handsets. More handsets exist than any other component of IP telephony, and this important touch point is an early part of the conversions from TDM- to IP-based telephony. A second point to understand about the enterprise IP Phone is that the IP Phone has traditionally been a hard endpoint, specifically a device that is a stand-alone with a physical link to the central site for power and connectivity. This is changing with the adoption of softphones installed on PC devices and 802.11 wireless WiFi phones that connect in any location where there is WiFi in the enterprise. Hardphones still make up the majority of the phones in the enterprise, but the growth rate for softphones is significant. Enterprise IP Phones Enterprise Class Hard IP Phones Soft IP Phones Deployed Enterprise Class WiFi Phones Deployed Figure 2-3 Enterprise Phone Growth Over the last 10 years, the enterprise class hard IP phone has gone through many changes. Initially, little difference existed between the IP Phones and the traditional TDM-based phones. One of the goals in the initial transition to IP Communications was to have the transition be as seamless as possible SO that the end users would not have to make any changes in behavior. This led to the r