1. 2/12/2001 ENUM Administration Penn Pfautz AT&T 732-420-4962 ppfautz@att.com

2. 2/12/2001 ENUM Administration Mixes domain registration and telephone number administration –Rights to ENUM domain tied to corresponding number assignment in the PSTN –Rights to number in ENUM lost when service on number is disconnected –Generally, telephone service provider is only party that knows about number assignments & disconnects –Design issue for industry & regulators: How to balance need for TSP involvement with burden on TSP and a competitive environment?

3. 2/12/2001 Tier 0 - e164.arpa (RIPE-NCC) nsnanp_enum.com (1.e164.arpa) 4.6.e164.arpa Sweden... $ORIGIN 3.7.9.1.e164.arpa. 7.8.7.6.6.3.2 IN NS e164.att.net. 8.8.7.6.6.3.2 IN NS joes-enum.com e164.att.net $ORIGIN 7.8.7.6.6.3.2.3.7.9.1.e164.arpa. IN NAPTR 10 10 "u" "sip+E2U" "!^.*$!sip:sdlind@sip.att.com!". IN NAPTR 102 10 "u" "mailto+E2U" "!^.*$!mailto:sdlind@att.com!". IN NAPTR 102 10 "u" "tel+E2U" "!^.*$!tel:+19732366787!". $ORIGIN e164.arpa. 1 IN NS nsnanp_enum.com 4.6 IN NS sweden_enum.com. Tier 1 – Registry- defined by ITU member state Tier 2 – Service Registrar ENUM Hierarchy sip.att.com Tier 3 – Application Service Provider

4. 2/12/2001 e164.arpa.arpa TLD since infrastructure RIPE NCC will host Essentially populated with identities of name servers for country codes ITU indicates to RIPE authority for each country code

5. 2/12/2001 Tier 1 (Registry) Entries point to Service Registrar for a number Provider(s) determined by national authorities –NANP-wide or per NANP nation? Because of number portability, Tier 1 name server must point to Service Registrar on an individual number basis; numbers cant simply be delegated to the carrier to which their Central Office code or thousands block was initially assigned

6. 2/12/2001 Tier 2 (Service Registrar) Hosts NAPTR (service) records for a telephone number All records for a given number must be in one name server Major issue is who can be Service Registrar –Two strawman models presented to IETF Any properly accredited domain name registrar (model I) Telephone service provider (model II)

7. 2/12/2001 Reference Model I (General) T1E T2E End User TSP ASP A B C F G E D New T2E H Legend ASP Application Service Provider TIE Tier 1 Entity (Registry) T2E Tier 2 Entity (Registrar) TSP Telephony Service Provider ** 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.

8. 2/12/2001 Reference Model I – Pros & Cons Pros: EU determines T2E, EU has more control EU can be T2E (e.g., universities and enterprises) for his/her own TN(s) Enable competitive T2E service offering Cons: More complicated interactions among involved entities More efforts at T2E to manage the NAPTR RRs

9. 2/12/2001 Reference Model II (T2E=TSP) T1E T2E/TSP End User Legend ASP Application Service Provider TIE Tier 1 Entity (Registry) T2E Tier 2 Entity (Registrar) TSP Telephony Service Provider ASP A C New T2E/TSP E B D ** 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.

10. 2/12/2001 Reference Model II – Pros & Cons Pros: Fewer interfaces to deal with Easier to verify EUs identity and ownership of the TN More incentives for TSPs to get involved in enum process (e.g., verify EUs ownership of a TN and inform T1E about TN service disconnect) Cons: Only TSPs can be T2E, non-competitive if there is only one TSP in a serving market Non-TSPs cannot be T2E –(except through delegation from TSP) EUs cannot be T2E for their own TNs EUs cannot get enum service if none of TSPs in the serving market offers enum service

11. 2/12/2001 Telephony Service Specific Records Are there services for which the TSP should have right to put records in ENUM? How can TSP control records in Tier 2 of end user choice? How might these records be distinguished? Alternative is to treat TSP like any other application service provider Ability of TSP to populate ENUM for customer will facilitate penetration

12. 2/12/2001 Major Issues Will the US populate its numbering resources in e164.arpa? Will the countries of the NANP take an integrated or independent approach to ENUM implementation? What entity or entities will provide Tier 1 functionality? What entities may be Service Registrars? How will authentication of rights to numbers be assured How will disconnect notification be handled? Will there be special telephony service specific records?