Understanding ENUM & Current Status Network Planning August 21, 2001

Understanding ENUM & Current Status August 21, A Record(A host Address) ARPA(Advanced Research Project Administration) DNS(Domain Name Server) E.164(ITU telephone numbering plan) IETF(Internet Engineering Task Force) ITU(International Telecommunication Union) MGC(Media Gateway Controller) NAPTR(Naming Authority Pointer Record in a DNS) NS(Authoritative Name Server, DNS record) RTP(Real-Time Transport Protocol) SG(Signaling Gateway) SGA(Study Group A of the International Telecommunication Advisory Committee, US policy and regulatory aspects telecommunications services.) SIP(Session Initiation Protocol) URI(Uniform Resource Identifiers) ACRONYMS

Understanding ENUM & Current Status August 21, e164.arpa.arpa The root node "" e164.arpa e164.arpa e164.arpain-addr third-level node second-level node.com second-level node.net This slide is from draft 4 of the Ad-Hoc Study Group A report on ENUM DNS Hierarchy

Understanding ENUM & Current Status August 21, e164.arpa Tier 0 Directs the DNS query to the controlling country based on country code. This is done by providing the NS record of Tier I. DNS service that stores a list of service specific internet addresses in the form of URI’s in a DNS resource record called NAPTR. TIER II will return the full list of Internet addresses associated with the E.164 number being queried. IN NAPTR "u" "sip+E2U" IN NAPTR "u" "mailto+E2U" IN NAPTR "u" ”fax+E2U" IN NAPTR "u" ”print+E2U" IN NAPTR "u" "tel+E2U" “!^.*$!tel: !” TIER 0, I, & II Tier I directs the DNS query to the customer Tier II provider. The NS record is provided for the subscriber’s telephone number. 1.e164.arpa Tier I.1.e164.arpa Tier II

Understanding ENUM & Current Status August 21, Requestor Requestor types into their browser a E.164 number: The requestor’s software converts the phone number With country code into a ENUM ready number e164.arpa Tier 0 database will direct the request to the North American Tier I database(s) based on the country code of 1. (Assumes specific model for Tier I.) The Tier II database will return to the requesting computer the list of service specific addresses (URIs) associated with the queried number. e164.arpa Tier 0 1.e164.arpa Tier I.1.e164.arpa Tier II. The Root Node The Tier I database, for country code 1, could be two sub-tiers; one sub-tier to receive country code 1 and the other to segment the NPAs within North America. The NPAs could be grouped by individual countries within North America. The root node is the root server that directs queries to the appropriate zone..arpa,.com,.org, etc Example

Understanding ENUM & Current Status August 21, FAX In this continued example, a requesting computer can deliver information to several devices just by knowing a phone number. This could be a number from a business card. Now the user can send information to a business associate based on the options returned by the query. e164.arpa 1.e164.arpa.1.e164.arpa. Example Continued

Understanding ENUM & Current Status August 21, TIER 0 – II DATABASES Tier 0:  Only one database controlled by RIPE NCC and ITU (policy only)  Contains participating country codes. Tier I:  Within North America there could be several Tier 1 databases.  There would have to be a delegation process from the North American country code of 1 to a NPA sub-database. The NPAs could be grouped by individual countries in North America.  Contains the fully qualified E.164 numbers and pointers to Tier II provider for the subscribers URIs. Tier II:  Competitive with many Tier II providers  Hosting the subscriber’s URIs

Understanding ENUM & Current Status August 21, United States Canada Jamaica Bahamas Grenada Barbados Barbuda & Antigua St. Kitts & Nevis St. Lucia St. Vincent & the Grenadines Dominica Trinidad & Tobago Dominican Republic Anguilla Bermuda British Virgin Islands Cayman Islands Commonwealth of the Northern Mariana Islands Guam Montserrat Puerto Rico Turks & Caicos Islands US Virgin Islands Countries Covered by the North American Code of 1 (One)

Understanding ENUM & Current Status August 21, Problem  More then one Country under the 1 code for North America  Who will administer the Tier I database for North America?  What happens if one of the other countries within North America respond to the ITU before the United States and are granted provisioning rights to the North American Code of 1?  Do we want to be involved with all the other Countries in North America for ENUM deployment?

Understanding ENUM & Current Status August 21, A Better Approach.e164.arpa 1.e164.arpa.1.e164.arpa United States NPAs.1.e164.arpa Dominica NPA.1.e164.arpa Barbados NPA.1.e164.arpa Jamaica NPA.1.e164.arpa Barbuda & Antigua NPA.1.e164.arpa Grenada NPA.1.e164.arpa Canada NPAs.1.e164.arpa ETC ….. Tier 0 (Containing list of country codes) Tier I for North America (Containing NPA pointers for each country that is a subset of the 1 code) Any Tier II Provider Tier I+(subset) would allow each country in North America to manage their own Tier I equivalent database.

Understanding ENUM & Current Status August 21, A Better Approach  Allows each country in North America to maintain their own Tier I equivalent database.  Reflects the fact that the United States is not the only entity within the 1 (one) code.  Once routed to the individual country Tier I database, the subscriber’s phone number and not the NPA will determine the Tier II provider for NAPTER records.

Understanding ENUM & Current Status August 21, ENUM Server Media Gateway STP Signaling Gateway MGC SSP Proxy Server A Proxy Server B ENUM enables PSTN to SIP calls 1 SIP: User B ENUM e164.arpa 5 4 Invite 3 2 Invite 6 Invite 7 User A Invite: From: Invite: SIP: From: In this example, User A attempts to contact User B who is on a VoIP network and uses a SIP phone. 1.User A dials the global E.164 number for User B. 2.The SSP sends an IAM message via SS7 to a SG (which is part of the Media Gateway Controller / Media Gateway). 3.The Media Gateway Controller sends an invite message to the nearest Proxy Server. 4.Proxy Server A does not know User B address; therefore it contacts an ENUM Server. 5.The ENUM Server returns the address of User B. 6.Proxy A sends invite message to User B’s Proxy Server B 7.Proxy Server B passes the invite to User B 8.If User B accepts the call, there is a two-way RTP path established between User B and the Media Gateway controller. A two-way path is also established between the Media Gateway and User A. At this point User A is able to communicate with User B. 8

Understanding ENUM & Current Status August 21, Competitive Model – Advantages & Disadvantages Advantages:  Any DNS provider can set up ENUM like structure in any Top Level Domain.  The DNS provider could provide all Tiers, 0 – II, and possibly root.  Provide Registrar Functions  Provide Register Functions  Can offer ENUM services outside of the United States. Disadvantages:  Will require clients and non-client to have resolver software.  Performance issues are a concern for clients and none clients  Major performance concerns for VoIP providers when ENUM is used as a location server.  Not compliant with RFC2916 from the IETF.  Not supported by the ITU-T Study Group 2.

Understanding ENUM & Current Status August 21, Status on ENUM  US Department of State Ad-Hoc Study Group A on ENUM Completed recommendation to Department of State.  Document Released on July 6. Presentation given to Study Group A on July 31.  Recommendations Recommendation for US participation in ENUM. Provides guidance to respond to ITU. Use the single zone per RFC 2916 (.arpa). Understand that there will be competitive models deployed. ENUM is an Opt In service. Privacy Protection is a high priority.  Scheduled Events August 27: First face-to-face meeting of the new ENUM Forum  Agree to forum principles and procedures  Agree to work plan  Pick leaders for the 5 proposed subcommittees. September 4: Next Study Group 2 ITU-T meeting.