{"id":2262,"date":"2008-08-12T15:33:06","date_gmt":"2008-08-12T19:33:06","guid":{"rendered":"http:\/\/blog.voipsupply.com\/?p=2262"},"modified":"2013-03-08T21:25:44","modified_gmt":"2013-03-08T21:25:44","slug":"ask-mr-andrews-what-is-enum","status":"publish","type":"post","link":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/ask-mr-andrews-what-is-enum\/","title":{"rendered":"Ask Mr. Andrews: What is ENUM?"},"content":{"rendered":"

Dear Mr. Andrews,<\/strong><\/p>\n

What is ENUM, and why should I care about it?<\/strong><\/p>\n

ENUM is a protocol developed by the IETF (www.ietf.org) that uses the Internet DNS system to translate traditional telephone numbers into IP addressing schemes.<\/p>\n

<\/p>\n

From the IETF ENUM Charter:<\/p>\n

The ENUM working group has defined a DNS-based architecture and
\nprotocol [RFC 3761] by which an E.164 number, as defined in ITU Recommendation
\nE.164, can be expressed as a Fully Qualified Domain Name in a specific
\nInternet Infrastructure domain defined for this purpose (e164.arpa).<\/p><\/blockquote>\n

ENUM allows for the lookup a dialed telephone number in DNS to see if there are alternate ways to set up the call instead of routing the call through the PSTN. ENUM may contain a reference to a SIP URL, a telephone number to dial, a web page or an e-mail address.
\nOnce a telephone number is entered, it is translated into an Internet address in the following manner:<\/p>\n

    \n
  1. The phone number is translated into a fully qualified E.164 number by adding the city (or area) and country code. Example: 545-1927 dialed in Washington, DC becomes +1-202-545-1927, where the “1” represents the North American country code. The “+” indicates that the number is a fully qualified E.164 number.<\/li>\n
  2. All characters are removed except for the digits. Example: 12025551234<\/li>\n
  3. The order of the digits is reversed. Example: 43215552021 (As DNS names are structured from right to left)<\/li>\n
  4. Dots are placed between each digit. Example: 4.3.2.1.5.5.5.2.0.2.1 (Each dot separates the number into administrative domains, or zones.)<\/li>\n
  5. The domain “e164.arpa” is appended to the end. Example: 4.3.2.1.5.5.5.2.0.2.1.e164.arpa (.arpa is the top level domain (TLD) used for ENUM)<\/li>\n<\/ol>\n

    ENUM answers the question of how network elements can locate services on the Internet using only a telephone number, and how telephones, with their limited input mechanism of twelve keys on a keypad, can be used to access Internet services. ENUM at its most basic is the convergence of PSTN and IP networks; it is the mapping of a telephone number from the public switched telephone network to Internet functionalities.<\/p>\n

    ENUM enables Internet-based users to make a selection from a range of services available for communicating with another person when the caller knows only a telephone number or has access only to a telephone keypad. ENUM allows users to access Internet-based services and resources from Internet-aware telephones, ordinary telephones connected to Internet gateways or proxy services, and other Internet-connected devices where input is limited to numeric digits.<\/p>\n

    ENUM enables users to specify their preferences for receiving incoming communications, and gives greater user control over communications. For example, a user can specify a preference for voice mail messages over live calls during certain times of day, or may indicate a destination for call forwarding.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Dear Mr. Andrews, What is ENUM, and why should I care about it? ENUM is a protocol developed by the IETF (www.ietf.org) that uses the Internet DNS system to translate traditional telephone numbers into IP addressing schemes.<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1219],"tags":[],"class_list":["post-2262","post","type-post","status-publish","format-standard","hentry","category-voip-education"],"_links":{"self":[{"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/posts\/2262","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/comments?post=2262"}],"version-history":[{"count":1,"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/posts\/2262\/revisions"}],"predecessor-version":[{"id":65164,"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/posts\/2262\/revisions\/65164"}],"wp:attachment":[{"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/media?parent=2262"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/categories?post=2262"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.voipsupply.com\/blog\/voip-insider\/wp-json\/wp\/v2\/tags?post=2262"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}