Enum is a technique of using the IP address of the VOIP end point that can be registered via DNS. With Enum now becoming a national movement VOIP will become mainstream reality. Like any other technology adoption US is lagging behind. In UK Nominet is running the Enum service which is a fantastic. The number is reversed and the 'e164.arpa' is added at the end for the node to be recognized with its IP address within the domain name system. A few more countries get involved in the Enum system and then you have a true PSTN parallel, reliable and affordable VoIP network that is truely reachable anywhere and everywhere and converged communication channel.