AT&T chief executive recently questioned the business model behin VOIP technologies. It's hardly a secret that many consumers buy into the VOIP hype to erase, or substantially lower, the cost of long dostance. The size of the market, when you compare the dollars spent on traditional telephone services and the money spent on VOIP, is hardly of interest to a multi-billion dollar corporation. In the United States, about 600,000 subscribers use commercial VoIP services, in which calls travel over the Internet rather than traditional phone lines. By comparison, more than 172 million homes use traditional phone lines, which are heavily taxed and regulated, meaning that consumers pay more in fees than actual phone costs.