Why ENUM ?

ENUM- --- S.,L. Chou 11

工業技術研究院電腦與通訊工業研究所Industrial Technology Research InstituteComputer & Communications Research Laboratories

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ENUM --- A Mechanism forPersonalized IP Services

ManagementUsing E.164 Number

周勝鄰博士工研院電通所

E-mail: [email protected]: 03-5915616

2003. 07

mailto:[email protected]





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Why ENUM ? 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?

Many Number & Addressing Mechanism Used

With ENUM Only One Number



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ENUM 101

What is ENUM (RFC 2916)?Make Telephone Number Become a Domain Name in InternetAny Telephone Number can Register As Domain Name in IP

World

Importance of ENUMNew Addressing Mechanism in IP WorldMechanism for IP/PSTN Convergence

Global ENUM Activities IETF, ITU-T, US ENUM Form, Europe, …ENUM Trials: More Than 10 Countries

Different Kinds of ENUMPublic (Personalized) ENUM: Future VisionCarrier ENUM: Enhance MMS/SMS ServicesEnterprise ENUM: Enhance Enterprise Telecomm Service



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What is ENUM ?

ENUMMechanism

E.164 Number

Domain Name System (DNS)

URI(Service@Host)

ENUM is a Mechanism to Translate an E.164 Number into A List of URI (Service@Host)

So that An IP User Can be Accessed by E.164 Number.

Problem: How to Address (or Locate) a User in IP World fromIP/PSTN Network ?

mailto:Service@Host



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ENUM Domain

1.e164.arpa

arpa

The root node “.”

...

7.1.e164.arpa

...

1.2.3.4.5.5.5.2.3.7.1.e164.arpa

e164.arpa in-addr.arpa

third-level node third-level node

second-level node

com

second-level node second-level node

net

Figure 1: A single common ENUM domain, which is e164.arpa



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Tier-0 Top Level Domain (TLD)

The Choice of Common Designated Domain fir ENUM Tier-0 is Undecided and is Proving ControversialARPA as ENUM TLD is Controlled by IETF and Operated by

RIPE-NCC US and some other countries, ISOC/IAB/IETF Support IETF

Conclusion European Union, France and Germany Proposed ITU-TSB as the

Operator for ENUM China, France, Germany, Syria and Spain Objected to ARPA as TLD

for political reason to reinforce the infrastructure of Internet governance

E.A-ENUM Recommendation “Principle and procedures for the administration of E.164 Country

codes for registration into the Domain Name System” TLD is open ITU-TSB is the ENUM Tier-0 Administrator



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ENUM in a Nutshell

• 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’ssip:[email protected]

• ask the DNS


Source: IETF



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ENUM in More Detail

“Call setup”

Sipsip:[email protected]

Query1.3.1.9.5.8.6.8.6.4.e164.arpa.?

Dial+4686859131

DNS-Server

Sip serverGateway

Responsesip:[email protected]

Source: IETF



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ENUM DNS Hierarchy

2.6.8.8.e164.arpa -> ns1.t1a.com; ns2.t1a.com6.6.8.8.e164.arpa -> ns1.t1b.com; ns2.t1b.com

4.3.2.1.4.9.3.2.2.6.8.8.e164.arpa-> NAPTR RRs (ldap URL)

LDAP DB

...

Tier 1

Tier 2(Designated bythe end user)

4.3.2.1.4.9.3.2.2.6.8.8.e164.arpa-> ns1.t2.biz; ns2.t2.biz

Tier 3(Depending onthe application)

6.8.8.e164.arpa -> ns1.t1.com ns2.t1.com

Tier 0(RIPE)

ns1.t1.com/ns2.t1.com

...4.3.2.1.8.9.2.6.6.8.8.e164.arpa-> ns1.t2.org; ns2.t2.org

ns1.t1b.com/ns2.t1b.comns1.t1a.com/ns2.t1a.com

ns1.t2.biz/ns2.t2.biz

ldap URL

Source: James Yum, Neustar

.arpa .



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ENUM Scenario

IP Network

Softswitch

SIP Proxy

IADIAD

ENUMServer

E-Mail Server

1

5

Dial:03-5915616

2

SIPPhone

3

3

0910961527

41. User Dial Tel. No2. ENUM Query, get 3 URIs3. Make SIP Call, No Answer4. Make Mobile Call, Fail5. Connect to E-Mail

DNS

$ORIGIN 6.1.6.5.1.9.5.3.6.8.8.e164.arpa. IN NAPTR 100 10 “u” “sip+E2U” “!^.*$!sip:[email protected]!” IN NAPTR 102 10 “u” “tel+E2U” “!^.*$!tel:+886910961527!” IN NAPTR 102 10 “u” “mailto+E2U” “!^.*$!mailto:[email protected]!”

Media Gateway

Signal Gateway

Enum Record



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ENUM Scenario (cont.)1. User Make Call to E.164 Number: 03-5915616

2. Softswitch Translates the E.164 Number to Query Input to ENUM Server:6.1.6.5.1.9.5.3.6.8.8.e164.arpa and gets a list of URIs returned

3. The Softswitch Processes the 1st URI Record,a. Query DNS to get the IP Address of Host: itri-sip-proxy.org.twb. Make SIP Call to SIP Phone of slchou through SIP Proxyc. SIP Phone Does not Answer

4. The Softswitch Processes the 2nd URI Record,a. Make PSTN Call Through Gateway to 0910961527b. 0910961527 Does not Answer

5. The Softswitch Processes the 3rd URI Record,a. Query DNS to get the IP Address of Host: itri.org.twb. Connect the Caller E-Mail Server SMTP Protocolc. Caller Leave the E-Mail Message



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ENUM and MMS Service

GGSN

Internet/Data Network

ENUM Server

MMS ‘A’

Gateway MMSC ‘B’

Step 3b

To: 0944-012345

Query:5.4.3.2.1.0.4.4.9.e164.apra

IP = 192.9.200.3

Network A

Network B

Registry Server

SGSN

Step 1

Step 2

Step 3a‘SMS Based’

Responsemms:0944012345@domainB



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ENUM Administrative Model



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Registry vs. Registrar Registry

Runs the DNS server for a specific domain nameone domain -> one registry

RegistrarProvide ENUM Registration to ENUM UsersSo that Users Need Not to Contact RegistryRegistrar verify customer data, do billing, and send data to

registry when delegation is to be done, changed or cancelled



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ITU-T ENUM Activities

ITU-T Study Group 2 Interim Procedures for Use of the ARPA Domain

Approved in May, 2002 Interim procedures for delegation of E.164 country codes into

ARPA domain before Approval of E.A-NUMRIPE-NCC is Authorized by ITU-TSB to Perform such Delegation

at this Stage http://www.ripe.net/enum/instructions.html



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IETF ENUM Activities Telephone Number Mapping (ENUM) WG

RFC 2916, “E.164 number and DNS” RFC 2915, “The naming authority pointer (NAPTR) DNS resource record”, August, 2000 RIPE-NCC

Related ENUM Activities after RFC 2916 Update RFC to reference the DDDS

– RFC2916bis,”The E.164 to URI DDDS Application” ENUM Administrative and Operational Prtocedures

– Registration and Provisioning Procedures, Validation and Authentication of Data– Operational Privacy, Security Issues and Procedure

IETF Liaison with ITU-T SG2 New Issues Being Considered:

– Extent Same URI in RFC 2916 for Different Service» e.g., 2 SIP URIs but one for voice and one is instant messaging

SIP vs. ENUM Services, e.g., distinction the location provided by SIP and ENUM Adding Presence as an ENUM service Extension of ENUM service ‘tel’ URI Location Number Portability, using DNS as the source Extensible Provisioning Protocol (EPP) in PROVREG WG, IETF



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886 Issue in IP World

6.8.8.e164.arpa

ENUM TLD

TaiwanENUM TIER 1

6.8.8.e164.arpaJPN ENUM

TIER 1

US ENUM TIER 1

ENUM TIER 2

ENUM TIER 2

ENUM TIER 2

ENUM TIER 2

ENUM TIER 2

• Permanent Caching 6.8.8.e164.arpa pointing to Taiwan ENUM Tier-1 in other Countries Tier-1



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ENUM Provisioning Issues Privacy Issues

Need to obtain end-user agreement to enter number in DNS, depending on national data-protection laws

Hardening the ENUM zone data against data mining, especially for the purposes of spam?

But hard to stop ENUM name servers being harvested for resources bound to an E.164 number

Security Issue Almost no security in normal DNS Transaction Signatures (TSIG) provides simple form of DNS Security

based on shared secret Ultimately DNSSEC needs to be deployed

uses public key encryption to generate digital signatures for every resource record in a zone

public keys are also signed and included in the zone, allowing the signatures to be validated



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ENUM Provisioning Issues Service Integrity

Unexpected Service Activated to the Caller

Service Provisioning and ManagementE.164 Number Authentication

Service Validation on NAPTR Modifications ?



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More Than Number Translation One E.164 Number to Multiple URIs

Multiple NAPTR service: URI

Multiple IP Services Behind one ENUM sip, tel, ifax, mms, ems, sip, e-mail, …

Service Realization Mechanism in IP WorldService Realization for ASPService Selection

Service Management for ENUM UsersWeb-based Service Management for ENUM UsersService Applied Dynamically



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Conclusions ENUM is An Important Enabling Technology to Speed-up

IP/PSTN Convergence ENUM --- Let Users Use Telephone Number in IP Network ENUM --- Make Users to Manage Different IP Services

Uniformly ENUM Will Bring Huge Impact to PSTN and IP Networks

Documents

Why ENUM ?