E.164 number and DNS (RFC2916)
Original Publication Date: 2000-Sep-01
Included in the Prior Art Database: 2019-Feb-13
Internet Society Requests For Comment (RFCs)
This document discusses the use of the Domain Name System (DNS) for storage of E.164 numbers. [STANDARDS-TRACK]
Network Working Group P. Faltstrom Request for Comments: 2916 Cisco Systems Inc. Category: Standards Track September 2000
E.164 number and DNS
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document discusses the use of the Domain Name System (DNS) for storage of E.164 numbers. More specifically, how DNS can be used for identifying available services connected to one E.164 number. Routing of the actual connection using the service selected using these methods is not discussed.
Through transformation of E.164 numbers into DNS names and the use of existing DNS services like delegation through NS records, and use of NAPTR  records in DNS  , one can look up what services are available for a specific domain name in a decentralized way with distributed management of the different levels in the lookup process.
The key words "MUST", "REQUIRED", "SHOULD", "RECOMMENDED", and "MAY" in this document are to be interpreted as described in RFC2119 .
2. E.164 numbers and DNS
The domain "e164.arpa" is being populated in order to provide the infrastructure in DNS for storage of E.164 numbers. In order to facilitate distributed operations, this domain is divided into subdomains. Holders of E.164 numbers which want to be listed in DNS
Faltstrom Standards Track [Page 1]
RFC 2916 E.164 number and DNS September 2000
should contact the appropriate zone administrator in order to be listed, by examining the SOA resource record associated with the zone, just like in normal DNS operations.
Of course, as with other domains, policies for such listings will be controlled on a subdomain basis and may differ in different parts of the world.
To find the DNS names for a specific E.164 number, the following procedure is to be followed:
1. See that the E.164 number is written in its full form, including the countrycode IDDD. Example: +46-8-9761234
2. Remove all non-digit characters with the exception of the leading ’+’. Example: +4689761234
3. Remove all characters with the exception of the digits. Example: 4689761234
4. Put dots (".") between each digit. Example: 188.8.131.52.184.108.40.206.3.4
5. Reverse the order of the digits. Example: 220.127.116.11.18.104.22.168.6.4
6. Append the string ".e164.arpa" to the end. Example: 22.214.171.124.126.96.36.199.6.4.e164.arpa
2.1 Special note about the ’+’
The ’+’ is kept in stage 2 in section 2 to flag that the number which the regular expression is operating on is a E.164 number. Future work will be needed to determine how other numbering plans (such as closed ones) might be identified. It is possible, but not definite, that they wo...