The Electronic Numbering (ENUM) system is used in conjunction with the Internet’s DNS system to map E.164 ITU standard (ordinary telephone) numbers to email addresses, web sites, VoIP addresses, and the like. An ENUM number is created in DNS by reversing the phone number, separating each digit with a period, and appending e164.arpa (the primary DNS zone). If you want Asterisk to perform ENUM lookups, configure the domain(s) in which to perform the lookups within the enum.conf file. In addition to the official e164.arpa domain, you can have Asterisk perform lookups in the publicly accessible e164.org domain.