1 ENUM? “ ” Telephone Number Mapping (ENUM or Enum, from TElephone NUmber Mapping) is a suite of protocols to unify the telephone numbering system E.164.

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ENUM?ENUM?

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Telephone Number Mapping (ENUM or Enum, from TElephone NUmber Mapping) is a suite of protocols to unify the telephone numbering system E.164 with the Internet addressing system DNS by using an indirect lookup method, to obtain NAPTR records. The records are stored at a DNS database.

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AssumptionAssumption

Use of standard telephone numbers is not going away• PSTN/analog

terminals are going to be around

• IP phones use 12-button keypad

• Globally unique identifier that has established familiarity with end users

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Problem statementsProblem statements

How do network elements (gateways, SIP servers etc) find services on the Internet if you only have a telephone (E.164) number?

How can subscribers define their preferences for incoming communications?

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More Problem StatementsMore Problem Statements

How do you address an IP-based voice terminal from the PSTN?

For a call that starts out as VoIP, how do you know to keep the call on the IP-plane (as opposed to the PSTN) for a dialed telephone number if the customer is not yours?

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Today, Many AddressesToday, Many Addresses

tel:+46-8-971234

mailto:paf@example.com

tel:+46-706051234

sip:paf@example.com

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With ENUM, Only OneWith ENUM, Only One

tel:+46-8-971234

mailto:paf@example.com

tel:+46-706051234

sip:paf@example.com

tel:+46-706051234

Give this number to friends:+46-8-971234

ENUM

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Solution in shortSolution in short

Put domain names derived from telephone numbers in the global domain name system, DNS

IETF ENUM Working Group created to solve the problem of using the DNS for:

•domain name in

• [Numbers re-formatted as domain names]

•URI out

• [mailto, sip, tel, http or other URI scheme]

Solution: NAPTR records

Use the URI’s for the communication

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NAPTRNAPTR

• take phone number +46-8-6859131

• turn into domain name 1.3.1.9.5.8.6.8.6.4.e164.arpa.

• return list of URI’s sip:paf@cisco.com

• ask the DNS mailto:paf@cisco.com

NAPTR stands for Naming Authority Pointer and is a newer type of DNS record that supports regular expression based rewriting.

Several NAPTR records can be chained together creating fairly sophisticated URL rewriting rules. A record can go through any number of rewrites before reaching a terminal condition.

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NetworkNetwork

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Tier 0

Tier 1

Tier 2

DomainName

System

ApplicationServiceProvider

Registrar

Registry

ENUMEnabled

Applications

Provisioning

• voice• fax• messaging & presence• email• web pages

Authentication &

ValidationEntities

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The Public ENUM Infrastructure

The Public ENUM Infrastructure

$ORIGIN e164.arpa. 3.7.9.1 IN NS nsnanp.enum.com . 4.4 IN NS UK_enum.com .…

$ORIGIN 3.7.9.1.e164.arpa. 7.9.7.6.6.3.2 IN NS e164.att.net .8.9.7.6.6.3.2 IN NS e164.xyz.com .…

$ORIGIN 7.9.7.6.6.3.2.3.7.9.1.e164.arpa. IN NAPTR 100 10 "u" "sip+E2U" "!^.*$!sip:19732366797@att.net!" .

e164.arpa

Tier 0 (Country Code Registry)

nsnanp.enum.com(3.7.9.1.e164.arpa)

Tier 1 (Telephone Number Registry)

e164.att.net

Tier 2 (Application Information)

International Implementation worked in IETF and ITU-T

National Implementation worked in ENUM Forum (US)

UK_enum.com(4.4.e164.arpa)

…

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Delegation of Country Codein Tier 0

Delegation of Country Codein Tier 0

Draft Recommendation E.A-ENUM in progress

Interim Procedures in place between IAB/ISOC and ITU-TSB• Use of e164.arpa pending outcome of

Recommendation• Country Code must be valid and assigned• Position of National Numbering Administrator

must be known and must opt-in

Similar situation for shared Network codes and codes for Groups of Countries (e.g., ETNS)

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Requirements DocumentRequirements Document

• Reference Architecture• Tier 1 Registry Operations, Security, & Admin• Tier 1 Performance Specifications• Privacy Considerations• Provisioning• Registrar Requirements• Authentication & Authorization• Tier 2 Requirements & Guidelines• Conflict Resolution• Issues Out of Scope

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Reference ArchitectureReference Architecture

Tier 1Registry

Tier 0

Root

Tier 2Provider

RegistrantRegistrant RegistrarRegistrar

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Reference ArchitectureReference Architecture

RegistrarRegistrantTier 1 Registry

o Does not address non geographic numbersTier 2 Service Provider

o Tier 2 contains the NAPTR records or delegations InterfacesIssue:

o One or More Tier 1 Providers– Delegation at Tier 0 by NPA

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Tier 1 AspectsTier 1 Aspects

Tier 1 Operationso Zone Information (aka zone files)o ContactInfo (aka WhoIs)o Reporting, backup, escrow & performance

requirementsPerformance Aspects

o DNS Performanceo EPP Interfaces

Tier 1 Security

Administrative Aspectso Dispute Resolutiono Data Collection and Privacy

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ProvisioningProvisioning

Tier 2Nameserver

RegistrarRegistrarTier 1

RegistryRegistrantRegistrant

Application ServiceProvider

Application ServiceProvider

Authentication & Validation Entities

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Provisioning AspectsProvisioning Aspects

Registrar Requirementso Registrant Validation & Authenticationo Dispute Resolutiono Registrar Infrastructure Requirementso Recommended Practices & Requirementso Various Scenarios

- Information Flows

Tier 2o Mostly Guidelines – SomeSome Requirementso Tier 2 may be self-provided or from a commercial 3rd

partyo Interfaces & Interactionso Performance Recommendations

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Future ActionsFuture Actions

Address implementation issues• Contracting model

• Integration/separation of North American countries

• Number of Tier 1 operators

Address Non-geographic numbers (specifically 8YY Toll Free)• Can’t be cleanly separated by North American

country

• Has unique provisioning requirements