ENUM (RFC 2916) is the Internet Engineering Task Force (IETF) protocol
that will assist in the convergence of the Public Switched Telephone Network (PSTN
) and the IP
network; it is the mapping of a telephone number from the PSTN to Internet
services — telephone number in, URL
out. ENUM was developed as a solution to the question of how to find services on the Internet using only a telephone number, and how telephones, which have an input mechanism limited to twelve keys on a keypad, can be used to access Internet services.