ENUM Activities in Japan- With Focus on Japan ENUM Study Group -February, 2003

Hiro Hotta
hotta@jprs.co.jp

JPRS (Japan Registry Service)1

Background information• March 2002
– Study Group on Telecommunications Service Numbering Plans(a kind of Government Advisory Committee)• It was recognized that ENUM be a candidate in managing therelationships between IP addresses and telephone numbers• How ENUM would fit Japanese situation should be studied• September 2002
– Japan ENUM Study Group was formally established after
consultation among various kinds of stakeholders– Members are from Industry and Academy– Observers from the Government• November 2002
– WIDE Project (General Chairperson, Jun Murai ) launched ENUM
Working Group– Its theme is trial and discussion about ENUM server/client
operation from the pure technology aspect– Won’t use 1.8.e164.arpa
2Telephone numbers in Japan• Phone numbers in Japan– Country code
– Administrator

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Ministry of Public Management, Home Affairs,Posts and Telecommunications– PSTN phones 0AB~J– Mobile phones 090xxxyyyyy, 080xxxyyyyy, 070xxxyyyyy– IP phones050xxxxyyyy• E.164 number is derived by– Putting area code at the top– Deleting leading “0”– Adding +81 at the top– Phone number of JPRS
• 5297-2571• 03-5297-2571• +81-3-5297-2571

in metropolitan Tokyoin Japan
E.164
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IP Telephone Numbers in Japan• 050xxxyyyyy are assigned to IP telephone services• They are “telephone numbers”– Subject to Telecommunications Business Law– Numbers are firstly assigned to telecom providers– Its network must be connected to PSTN
– It must have telephone-level quality (sound quality,communication delay, …)• They are the equivalents to traditional phones whenseen from PSTN
– Connected to switches via media gateway• IP network is used only in the providers’ system• Way of connection between/among providers– with ENUM
– with SIP without ENUM
– with Proprietary mechanism
4Japan ENUM Study Group5

Background of Establishment• ENUM technologies– being standardized in IETF
– specifications almost fixed• Policy of International Operation– have been discussed and becoming more well-defined in ITU-T– published as Supplement Document• ENUM trial environment– being prepared by IAB，RIPE NCC，ITU-T, etc.
– being under trial in several countries• In Japan– 050xxxxyyyy is being assigned to IP telephones– IP telephone services are rapidly growing- ENUM should be well studied and understood- How ENUM is used should be made clear
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Objectives• Understanding the ENUM technology• Studying the implementation and operation of
the ENUM–based system, and related matters• Finding political/regulatory issues related toENUM-based implementation and operation• Finding technological issues related to ENUM
• Clarifying pros and cons in ENUM usage

The followings are studied- ENUM technology- Related technology such as DNS，URI，DDDS
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Members• Chair– Shigeki Goto (Waseda Univ.)• Vice Chair– Susumu Sano (JPNIC)• Secretariat– JPNIC• Members (23)– Telecommunication companies– IP telephone service providers– Network Device Vendors– Network Solution Providers– ccTLD registry (JPRS)– Trading companies– Non-profit organizations– Professionals from universities• Observers– Ministry of Public Management, Home Affairs, Posts andTelecommunications

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Scope• ENUM technology itself• Some issues happening after resolving the telephone
number mapping may be important to implement anddeploy the service, but they are out of scope on current
Japan ENUM Study Group• examples that are out of scope– fee/charge arrangement– authentication in the phase of communications between users– security of communications between users– improper use• spamming• direct-mails• etc.

– quality and reliability of communications between users

9What will ENUM solve• Expected usage– Identification of applications by E.164 numbers– Solving Telephone number mapping in calling fromtraditional telephones to Internet telephones– Solving telephone number mapping in calling fromInternet telephones to traditional telephones– Solving telephone number mapping within atelephone network (including an IP telephonenetwork)• Implementation and operation, management
structure are different in each way of usage
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Tier Structure• Tier structure and DNS zone structure– Country dependent– Existing structures of Telecom and Internet-relatedindustry should be considered and a new
combined/compromised structure may be needed toadopt ENUM (further discussion needed)• Recommendation– Boundary between Tier0 and Tier1 is 1.8.e164.arpa• as +81 is used for subscribers if and only if in Japan– Boundary between Tier1 and Tier2 has some options• Examples are shown in next pages

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Boundary between Tier1 and Tier2 (model1)
Tier1 has phone numbers in full and no Tier2 is introduced
e164.arpa
Tier0
1.8.e164.arpa

Tier1

This model gives stable coherent
services to all the subscribers.

telephone numbers
NS record

NAPTR record

12Boundary between Tier1 and Tier2 (model2)
Tier1 has phone numbers in full and Tier2 handles
a NAPTR record of each number.
e164.arpa
Tier0
1.8.e164.arpa

Tier1
Each subscriber can choose Tier2
provider to get preferred service.

telephone numbers
Tier2
NS record

NAPTR record

13Boundary between Tier1 and Tier2 (model3)
Boundary corresponds to the chunks (10,000numbers) assigned to Telecom providers.
e164.arpa
Tier0
1.8.e164.arpa
Telephone provider and Tier2 registry
can be the same, in which case themanagement of users may be efficient.

Tier1

050xxxx

090zzzz

050yyyy

. . .

Tier2

telephone numbers
NS record

NAPTR record

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Boundary between Tier1 and Tier2 (model4)
Tier1 is divided into groups corresponding to chunks,
each represents a phone service for example.
e164.arpa
Tier0
1.8.e164.arpa
for example, 050 for IP phones and090 for mobile phones

050

Tier1

050xxxx

090

090zzzz

050yyyy

. . .

Tier2

telephone numbers
NS record

NAPTR record

15DNS Zone structure for ENUM
• A single or multiple DNS zones will be
introduced to manage each unit of each Tier.
• single / multiple will be chosen by eachmanager of each unit
– easiness of management– efficiency of provisioning– efficiency of resolution– etc.

• The chunk of phone numbers that registrar
handles does not necessarily correspond to aDNS zone
– in case of correspondence• Authentication of record-change is easier– in case of non-correspondence• Authentication of record-change requires more caution inimplementing access to each NAPTR record

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User ENUM and Operator ENUM
• User ENUM and Operator ENUM
– Definitions of them were inevitable in carrying forward a
discussion– Definition should have been done with our words and withknowledge of national telecom industry structure• User ENUM
– Each user of E.164 number, who subscribes a telecom
service identified by the number, registers his/her favorite
application services to ENUM records at his/her will
– IETF, UKEG, ENUM Forum(US) seem to mainly give focus on
this category• Operator ENUM
– A provider, which has assigned the number to the user, uses
ENUM records to implement its service identified by thenumber at its will
– This receives interests from IP telephone service providers inJapan• Combined models of User and Operator ENUM
– Addition of User ENUM flavor to Operator ENUM
– Addition of Operator ENUM flavor to User ENUM17Features of User ENUM & Operator ENUM

registered byobjectives

User ENUM

Operator ENUM

useroperator

to publicize services intended
to publicize services toby the user
implement the operator’s service

URIs

Various (as users like)

URIs to identify the operator’sservices

phone numbers
managed byuser or operator

operator

accessed byInternet users

subscribers or network devicesof the operator

authenticationof accesses

from large number of users

from small number of operators

security

Internet level

determined by the operator

quality of DNS

Internet level

determined by the operator
18Future activity• More investigation on implementation and operation ofUser ENUM and Operator ENUM will be put forward• Requirements will be investigated for both User ENUMand Operator ENUM
– Efficiency– Function– Reliability– Security– Privacy– Management structure of DNS– Provisioning process– etc.

• Issues in each model will be clarified• Experiment/trial will be done
– to identify issues not extracted by the desk work
– to elaborate practical solutions

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More on the future• Business structure– Structure of Tier1s and Tier2s ?
– Who are the providers of Tier1 and Tier2 ?
– How to cover the cost of ENUM system andoperation ?

• Relationship with telephone numbering system– Whom does each phone number belong to?
– What does phone number identify ?
• Phone service ?
• Is User ENUM violate the policy of telephone numbers?

• More clarification of demands needed– Usage of phone numbers in the Internet ?
– Common database among IP telephone service
providers ?

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