A standard (RFC 2916) issued by the Internet Engineering Task Force (IETF) for translating between PSTN and Internet addresses. ENUM translates between PSTN telephone numbers, as specified by the ITU-T in E.164, and Internet Protocol (IP) addresses, as specified for IPv4 in RFC 791 and IPv6 in RFC 2460. ENUM requires that both E.164 and IP addresses be registered with the ENUM Domain Name Service (DNS), which can be consulted by gateways that interconnect the two disparate networks. Thereby, a given call can traverse both the PSTN and the Internet or other IP-based packet network. See also DNS, E.164, gateway, IETF, Internet, IP, IP address, IPv4, IPv6, ITU-T, PSTN, RFC, and telephone number.