E164.org is a public enum directory of telephone numbers that can be
reached over the Internet by anyone anywhere!

The system works by publishing a DNS zone, 'e164.org', that can be used
by various Internet applications including SER, Gnome Meeting and
Asterisk. The idea is to be able to map your phone number to an Email
address, website, VoIP addresses, etc.

WWW: http://www.e164.org/