ENUM Administration Issues

1. ENUM Administration Issues Some numbering perspectives ITU-T ENUM Workshop Geneva 17 January 2001 Steve Lind AT&T sdlind@att.com Tony Holmes BT tony.ar.holmes@bt.com

2. Agenda • WP1/2 Liaison to IETF/ISOC • Some typical call flows • ENUM DNS structure and Hierarchy • ENUM Considerations and issues • A glossary of terms used can be found at the end of this slide pack

3. The Aim of this session • To help raise awareness and assist administrations in understanding what needs to happen to make ENUM work • To consider the administration requirements of ENUM • To identify issues • …..not only those that need to be tackled by the ITU but also by Member States and other parties

4. WP1/2 Liaison to IETF/ISOC • Results of DNS Administrative discussions and Contributions - October 2000 ITU-T WP1/2 Meeting - Berlin. • Understandings regarding the method for administering and maintaining the E.164-based resource data in the DNS. • Administration = provision and update of E.164 numerical values, of domain “e164.arpa”, in the DNS. • Example of “e164.arpa” domain name: 1.5.1.5.0.2.0.4.1.3.3.e164.arpa • Administrative Zones defined: e164.arpa = Domain Zone 3.3 = Country Code Zone 1.5.1.5.0.2.0.4.1 = National Zone Note: Here ‘Zone’ refers to a segment of the domain name

5. WP1/2 Liaison to IETF/ISOC • Agreements regarding the administration of Zones • Domain Zone is outside the scope of the ITU • Country Code Zone • ITU provides assignment data to the DNS Administrator • ITU Member States authorize/deny the ITU to notify the registrar of E164.arpa to include their Country Code • No data entry for “spare” or test codes • National Zone • National Matter - determined by each Member State • Shared Network Codes - each entity determines • Groups of Countries - the administrative entityfor theGroup determines, in consultation with participating Member States

6. WP1/2 Liaison to IETF/ISOC • Other Agreements • Once data input is authorized, each Member State/Administrative Entity is responsible for update and accuracy of data. • Data not authorized for input will not be entered in the DNS. • All Administrative Entities (including the DNS Administrator) will adhere to the tenets of pertinent ITU Recommendations e.g. E.190, E.164 etc. • WP1/2 will provide guidance to assist the Member States and Administrative Entities in the performance of their responsibilities - the purpose of this meeting.

7. +41 22 730 5887 DNS look up returns NAPTR record with itu@sipservice.foo DNS SIP server routes call to user DNS returns SIP server IP address IP Network 6 2 1 5 4 7 3 +44 1473 123456 +41 22 730 5887 Gateway looks up host for itu@sipservice.foo PSTN Gateway +41 22 730 5887 ( ENUM functionality) formats url 7.8.8.5.0.3.7.2.2.1.4.e164.arpa Typical call flows PSTN - IP

8. DNS returns record as url tel:+441473123456 +41 22 730 5887 DNS +44 1473 123456 Client formats url Location server SIP Client initiates INVITE to server using tel url IP Network LS returns IP address of Gateway 5 1 4 8 2 3 6 7 SIP sever looks up gateway address from LS +44 1473 123456 Call routed to Gateway IP address PSTN Gateway Gateway completes call to PSTN Typical call flows IP - PSTN

9. ENUM - DNS Structure & Hierarchy e164.arpa RIPE NCC Tier 1 Registry 4.4.e164.arpa Tier 2 Service Registrar 1.6.e164.arpa Tier 3 Application Service Provider

10. ITU & IETF position states: ITU has responsibility to provide assignment information. Geographic Country Codes will only be included in the DNS when authorised by the Member State responsible for that code ENUM Considerations - 1 Inserting numbers in the DNS Tier 1 Registry • Registries will be identified by each participating Member State • Entries will point to the Service Registrar for a number • ISSUE • An agreed process needs to be developed e.g. between appropriate authorities (participating Member States, potentially ITU-T) and Tier 1 Registries

11. ENUM Considerations - 2 Inserting numbers in the DNS Tier 1 Registry ITU & IETF position states: Each administration is responsible for ensuring DNS administrators (Registries) are aware of appropriate changes • ISSUES • Maintaining integrity of E.164 • Building ENUM integrity • Not all countries have the same regulation or rules of administration BUT all need to address the same issues for ENUM • How should Tier 1 Registries be selected? • - it’s a national matter • but there are options…….

12. ENUM Considerations - 3 Inserting numbers in the DNS Tier 1 Registry • …could be one or more Tier 1 Registry providers per CC e.g. • - integrated number plan could be separated by national authorities • - Tier1 Registry(s) could be separated by number ranges within a CC but there can only be one Registry per E.164 number • ISSUES • How to determine the most appropriate arrangement? • Who runs national Registries? • An agreed process needs to be developed between participating Member States and their Tier 1 Registry provider(s) • (national matter).

13. Inserting numbers in the DNS Tier 1 Registry ITU & IETF position states: For national zone resources behind the CC shared by Networks the resource assignee is responsible for providing E.164 assignment information to the DNS Administrator ITU & IETF position states: For national zone resources behind the CC shared by Groups of Countries the resource assignee is responsible for providing E.164 assignment information to the DNS Administrator ENUM Considerations - 4 • Network Code assignees need to be made aware of ENUM rules • ITU Recs may require amendment to embrace this • ITU Recs may require amendment/development to embrace this

14. ENUM Considerations - 5 Inserting numbers in the DNS Tier 1 Registry e164.arpa Tier 1 Registry Tier 2 Service Registrar Entries in the Tier 1 Registry point to the Service Registrar for an E164 number • ISSUE • In some cases with Number Portability, the name server must point to a Service Registrar on an individual E164 number basis, not a number block • The full implications on all methods of NP and associated processes need to be understood

15. Inserting numbers in the DNS Enables the use of an E.164 number allocated to a Service Provider to be used to deliver calls to another Service Provider ENUM considerations - 6 • ISSUES • Network by-pass • Some countries are moving to single number administration and payment for numbers, does this raise additional issues? • Rights of ownership? • - differences across administrations? • - Intellectual Property Rights?

16. ENUM considerations - 7 Inserting numbers in the DNS Enables the use of an E.164 number allocated to a Service Provider to be used to deliver calls to another Service Provider • ISSUES • Customer perception where an E.164 number that provides access to an ISP, other than the one responsible for the number, experiences differing QoS and cost? • Privacy of information/consumer protection • Legal intercept? • Regulatory implications • e.g monitoring of QoS etc?

17. ENUM Considerations - 8 Inserting numbers in the DNS Tier 2 Service Registrar e164.arpa Tier 1 Registry points to Registry Tier 2 Service Registrar points to Service Registrar for an E.164 number hosts NAPTR records for E.164 numbers All records for a given number must be in one name server Two alternatives under discussion Model 1 - any accredited domain name/service registrar Model 2 - telephone service provider • ISSUE • Determination of who qualifies to be a Service Registrar?

18. Reference Model I (General) Legend ASP Application Service Provider T1E Tier 1 Entity (Registry) T2E Tier 2 Entity (Registrar) TSP Telephony Service Provider EU End User T1E New T2E A H ** End User can be the end user itself or an agent authorized to represent the end user. ** TSP can offer application services also. The “TSP” entity performs functions specific to the TSP. B C T2E E U F G E D TSP ASP

19. ENUM Considerations - 9 A H E U TSP Reference Model I New T2E T1E Model I Pros & Cons C T2E B G F E D ASP • Pros: • EU determines T2E, EU has more control • EU can be T2E (e.g., universities and enterprises) for his/her own E.164 number(s) • Enable competitive T2E service offering • Cons: • More complicated interactions among involved entities • More efforts at T2E to manage the NAPTR RRs

20. Reference Model II (T2E=TSP) T1E Legend ASP Application Service Provider T1E Tier 1 Entity T2E Tier 2 Entity TSP Telephony Service Provider EU End User A’ B’ T2E/TSP E U ** End User can be the end user itself or an agent authorized to represent the end user. ** TSP can offer application services also. The “TSP” entity performs functions specific to the TSP. E’ C’ D’ ASP New T2E/TSP

21. ENUM Considerations - 10 Reference Model II • Pros: • Fewer interfaces to deal with • Easier to verify End Users’s identity and ownership of the E.164 Number • More incentives for TSPs to get involved in ENUM process • (e.g., verify End User’s ownership of a E.164 Number and inform T1E about E.164 number service disconnect) T1E B’ A’ T2E/TSP E U E’ C’ D’ New T2E/TSP ASP • Cons: • Only TSPs can be T2E, non-competitive if there is only one TSP in a serving market • Non-TSPs cannot be T2E • End Users cannot be T2E for their own E.164 Numbers • End Users cannot get ENUM service if none of TSPs in the serving market offers ENUM service

22. Inserting numbers in the DNS Tier 2 Service Registrar ENUM Considerations - 11 Some Administration issues from the Service Registrar models • Is one, or a number of different model(s) preferable? • Who should be Service Registrars? • How can E.164/DNS integrity be safeguarded if responsibility for number insertion in the DNS lies with the customer? • How should validation of subscriber identity, data & NAPTR (service records) occur? • How can number/name hijacking/fraud be prevented?

23. ENUM Considerations - 12 Inserting numbers in the DNS • ISSUES • How will number changes/number churn be handled? • How will ceased numbers be notified/recovered? • Could prepaid mobile numbers be inserted? • If so how will ownership be validated ? • How will changes/ownership/loss/ theft/cease issues be addressed? • Who has these responsibilities?

24. ENUM Considerations - 13 Inserting numbers in the DNS • ISSUES • Geographic numbers would lose location information, will begin to look more like personal numbers • Impact on number plans/number administration? • Are additional controls required where numbers are shared? • Should/could requirements on carriers/third parties be enforced? • Do ENUM procedures and rules apply if E.164 numbers are inserted in other domain name space (e.g .com/other domains) ?