SIST-TS ETSI/TS 102 172 V1.1.1:2005

SLOVENSKI STANDARD
SIST-TS ETSI/TS 102 172 V1.1.1:2005
01-januar-2005
Storitve in protokoli za napredna omrežja (SPAN) – Najmanjše zahteve za preskuse
vzajemne obratovalnosti evropskega ENUM
Services and Protocols for Advanced Networks (SPAN); Minimun requirements for
interoperability of European ENUM trials
Ta slovenski standard je istoveten z: TS 102 172 Version 1.1.1
ICS:
33.040.30 Komutacijski in signalizacijski Switching and signalling
sistem systems
SIST-TS ETSI/TS 102 172 V1.1.1:2005 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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Intellectual Property Rights................................................................................................................................4

Foreword.............................................................................................................................................................4

1 Scope........................................................................................................................................................5

2 References................................................................................................................................................5

3 Definitions and abbreviations...................................................................................................................6

3.1 Definitions..........................................................................................................................................................6

3.2 Abbreviations.....................................................................................................................................................7

4 Introduction..............................................................................................................................................8

5 General objectives of ENUM trials within Europe ..................................................................................9

6 ENUM trial interoperability ...................................................................................................................10

6.1 Constraints in national trials.............................................................................................................................10

6.2 Interoperability in ENUM trials .......................................................................................................................12

6.3 Application recommendations to facilitate trial interoperability......................................................................13

7 Administrative requirements for interoperability of trials......................................................................13

8 DNS requirements for interoperability of trials......................................................................................14

9 Harmonization of the "ENUMservice" field in the NAPTR Records ....................................................14

9.1 Background to minimum requirements for NAPTR use ..................................................................................14

9.2 General conditions............................................................................................................................................15

9.3 Format and processing of NAPTR records.......................................................................................................16

9.4 "ENUMservices" and associated URI Schemes ...............................................................................................17

9.4.1 Minimum set of "ENUMservices"..............................................................................................................17

9.4.1.1 "ENUMservices" for Interactive Media-stream Exchange....................................................................17

9.4.1.2 "ENUMservices" for Discrete (non-session related) Messages ............................................................17

9.4.1.3 "ENUMservices" for Information Source .............................................................................................18

9.4.1.4 "ENUMservices" for Service Resolution Services................................................................................18

9.4.1.5 "ENUMservices" for Session-oriented Message Exchanges.................................................................18

9.4.1.6 "ENUMservices" for Instant Information Display - Announcement.....................................................19

9.4.1.7 "ENUMservice" for Redirection ...........................................................................................................19

9.4.2 Additional "ENUMservices"......................................................................................................................20

9.4.2.1 "ENUMservices" for Location Information ..........................................................................................20

9.4.2.2 "ENUMservices" for Public Key Information ......................................................................................20

10 Processing of retrieved information by ENUM Clients .........................................................................20

10.1 Generic ENUM Clients ....................................................................................................................................20

10.2 ENUM enabled Application Clients.................................................................................................................21

10.3 Examples of specific ENUM enabled Application Clients ..............................................................................21

10.3.1 ENUM enabled SIP Client..........................................................................................................................21

10.3.2 ENUM enabled H323 Client.......................................................................................................................21

10.3.3 ENUM enabled Email Client......................................................................................................................22

10.3.4 ENUM enabled Web Browser ....................................................................................................................22

10.3.5 ENUM enabled FTP Client.........................................................................................................................22

10.3.6 ENUM enabled FAX Client........................................................................................................................22

10.3.7 ENUM enabled SMS Client .......................................................................................................................22

10.3.8 ENUM enabled Location Client .................................................................................................................22

Annex A (informative): Background to NAPTR Resource Records..................................................23

Annex B (informative): Bibliography...................................................................................................26

History ..............................................................................................................................................................27

IPRs essential or potentially essential to the present document may have been declared to ETSI. The information

pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found

in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in

respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web

All published ETSI deliverables shall include information which directs the reader to the above source of information.

This Technical Specification (TS) has been produced by ETSI Technical Committee Services and Protocols for

The present document contains general guidance on European ENUM trials and the specification for:

• The format, contents and meaning of the information in the NAPTR records that are held by the ENUM Tier 2

• The ways in which ENUM client software should interpret and act upon information obtained from NAPTR

The present document is intended to enable interoperability between ENUM trials that are organized in different

• The same ENUM client software to work with NAPTR records generated by different national trials and this

in turn will enable applications that use ENUM to access details of ENUM subscribers in more than one

• Organizations to function as ENUM Registrars and ENUM Tier 2 Nameserver Provider in more than one

The present document will therefore add economies of scope to the ENUM trials that will benefit ENUM subscribers,

The present document is published as a Technical Specification (TS) at this stage as the contents are unproven. The

intention is to update and upgrade the present document in the light of the results obtained from the trials.

These requirements are therefore specified for the trial phase only, and as such impose no constraints on ENUM when

Although the present document is focused towards European ENUM trials its use could facilitate interoperability with

The following documents contain provisions which, through reference in this text, constitute provisions of the present

• References are either specific (identified by date of publication and/or edition number or version number) or

Referenced documents which are not found to be publicly available in the expected location might be found at

NOTE 1: The present document is based additionally on "Work in Progress" at the IETF, documented in Internet

Drafts. This is especially valid for the syntax of the "ENUMservice" field in the NAPTR RR, which is

based on the definitions in Internet Draft , which will supersede

RFC 2916. Within the present document this Internet Draft is referenced as RFC 2916bis.

[1] ITU-T Recommendation E.164: "The international public telecommunication numbering plan".

[8] IETF RFC 2181: "Clarifications to the DNS Specification", Updates: 1034, 1035, 1123.

[18] IETF RFC 3401: "Dynamic Delegation Discovery System (DDDS) Part One: The Comprehensive

[19] IETF RFC 3402: "Dynamic Delegation Discovery System (DDDS) Part Two: The Algorithm".

[20] IETF RFC 3403: "Dynamic Delegation Discovery System (DDDS). Part Three: The Domain

[21] IETF RFC 3405: "Dynamic Delegation Discovery System (DDDS) Part Five: URI.ARPA

For the purposes of the present document, the terms and definitions given in TS 102 051 [2], with the exception of

NOTE: The term ENUM End user is not used within the present document, ENUM User and ENUM Subscriber

ENUM Subscriber: assignee of an E.164 number who has agreed to insert its E.164 number in the ENUM DNS-based

NOTE: The ENUM subscriber has full control over the provision and content of the NAPTR Resource Records in

the ENUM Tier 2 Nameserver provider. The ENUM Subscriber is called ENUM End User in

ENUM User: person or entity who is querying the ENUM DNS-based architecture using an ENUM-enabled

NOTE: The ENUM User may be aware only of the application and not of the use of ENUM by the application.

Application Client: function that provides a user access to the Application Server, e.g. a VoIP client or e-mail client

Application Server: function provided by an Application Service Provider to communicate with the Application Client

ENUM Client: function that provides access to the DNS which will then return information in the form of NAPTR

NOTE: This could take several forms e.g. it may reside as client software on an intelligent terminal used directly

by the ENUM User or be network based, provided upstream as part of the facilities offered by an

ENUM enabled Application Client: Application Client querying ENUM directly for NAPTR Resource Records

ENUM enabled Application Server: Application Server that is using ENUM Clients as part of their application,

e.g. an email server that translates phone numbers in the To:/RCPT fields into their ENUM stored mailto: values

"ENUMservice": parameter held in the Service Field of a NAPTR Resource Record associated with the ENUM DDDS

NOTE: According to RFC 2916bis an "ENUMservice" must be registered with the IANA via a description in an

Naming Authority Pointer Resource Record (NAPTR): The Naming Authority Pointer Resource Record is specified

Resource Record: element within the Domain Names System (DNS) containing a data item associated with a domain

Uniform Resource Identifier (URI): compact string of characters for identifying an abstract or physical resource

NOTE: An URI is used within a NAPTR Resource Record to point to a specific application.

Uniform Resource Identifier (URI) Schemes: In the Uniform Resource Identifier (URI) definition (RFC 2396,

In addition, the not yet registered URI Schemes "h323" and "ENUM" are used. The "tel" URI Schemes is also currently

undergoing modifications. For more information see the related Internet Drafts (work in progress).

ITU-T International Telecommunication Union - Telecommunication Standardization Sector

WHOIS A tool (program) to look up domain names and related information in a database

Following initial work on the national ENUM trials that are either being planned or taking place in several European

countries, it has been recognized that additional benefits can be gained by facilitating interoperability of the various

trials. The present document aims to assist those countries who wish to expand their trials on a pan-European basis. It

ENUM Trial interoperability would enable benefits to be gained by sharing experience of different administrative,

technical, operational and user aspects relating to the provision of ENUM capabilities between countries. Each country

will have its own particular architectural, administrative, security and authentication requirements along with its

particular implementation rules. Therefore linking the trials together will enable the various approaches to be evaluated

on a broad basis. This approach would also widen the range of applications and services available to end users as it will

Without commonality of some aspects especially as the format of the NAPTRs designed to support applications,

attempts to link trials together are likely to result in difficulties when trying to access user information in more than one

The results collected from pan-European trials should enable participants to gain valuable information and experience

Involved parties are interested in carrying out trials for ENUM implementation in order to further the resolution of

technical, administrative and operation issues that may define the rules for the commercial deployment in that country.

In order not to presume any implementation solution, it is necessary that the minimum sets of requirements will not

limit the freedom of individual trials and the possibility to take different approaches.

The range of functional entities participating in a national trial depends on the choice of the administrative model in the

country involved. The preferred model in a given country, in turn, depends on, among other things, the national

arrangements for the management of domain names and E.164 numbers. TS 102 051 [2] outlines a number of options

for the administrative model and explains the functions of these roles. Nonetheless, most of the roles (functional

entities) listed are expected to be present in all European trials irrespective of the chosen administrative model:

Although the objectives for ENUM trials undertaken within any European country must remain totally a national

matter, it should be recognized that additional benefits may be gained from shared experience if some of the general

objectives are shared. Such experience can be further enhanced if different implementations are linked together.

The following list of objectives identifies those that fall into this category and is recommended for trials that are linked

• Understanding the ENUM technology and its potential in providing new applications and services to

• Evaluating basic DNS infrastructure in relation to ENUM architecture models (for example ENUM Tier 1

Registry, ENUM Registrar, ENUM Tier 2 Nameserver Provider, Authentication and Validation procedures).

• Evaluate and refine the economic benefits and costs of introducing the ENUM capability.

• Exchange of information related to processes e.g. provide process, change process, cessation process, dispute

Additionally the following list identifies aspects where additional benefits are likely to be gained, although their

inclusion should be dependent upon each specific case and should remain a national issue:

• Experience of registering the ENUM domain name related to the E.164 number and the entry of the necessary

• Validation initiated by the ENUM Registrar (that the correct delegation is made to the ENUM Subscriber).

• Gaining experience in provisioning ENUM delegation processes between ENUM Registrars and ENUM Tier 1

• Exploring options for harmonized provisioning protocols across different countries as well as for unified

• Experience of sharing a common set of applications (e.g. VoIP) from a wider set of users.

This clause analyses the issues of interoperability and the constraints on the different roles of the parties involved in

The ENUM Subscriber in a national trial needs to have an E.164 number in the country concerned. Subscribers outside

the countries running ENUM trials have no possibility of involvement as they will not have an E.164 number that can

be supported in the .e164.arpa part of DNS. Since DNS is open, the data relating to all ENUM subscribers is visible to

The ENUM Registrar acts as an agent to input the ENUM Subscriber's ENUM domain name (E.164 number) into the

ENUM Tier 1 Registry so that the Registry points to the correct ENUM Tier 2 Nameserver Provider in DNS. The

ENUM Registrar needs to be appointed or recognized by the ENUM Tier 1 Registry. The ENUM Registrar may also

have access to the ENUM Tier 2 nameserver to load, amend and delete NAPTR records in the format being used by the

country concerned, or the ENUM Subscriber may load, amend and delete the NAPTR records directly with the

nameserver themselves. Thus the ENUM Registrar's role is nationally specific, although the Registrar may be located

The ENUM Tier 2 Nameserver Provider holds the NAPTR records in the format being used by the country

concerned. The ENUM Tier 1 Registry for the country concerned needs to point to that nameserver. The nameserver

The ENUM Client Supplier is tied to the format of the NAPTR records for the national trial because their ENUM

Clients need to be compatible with the NAPTR records. ENUM Clients may be embedded in Application Clients or

Application Server or may be run as simple stand-alone applications. If the NAPTR records have different formats for

different trials then different versions of the application would be needed to work with ENUM Subscribers in more than

The Application Service Provider may use ENUM Clients as part of their application. The Application Service

Provider using ENUM may be located anywhere, even in a country that is not running an ENUM trial at all. An

Application Service Provider not using ENUM is out of scope of this specification.

The ENUM User may be located anywhere but, depending on the application, may need special Application Client

Figure 1 shows the relationships involved for two different national trials and for a common model of the relationship

between ENUM Tier 1 Registry, ENUM Registrar and ENUM Tier 2 Nameserver Provider. The ENUM Subscriber

establishes their ENUM entry through the ENUM Registrar who loads this information into the NAPTR records held by

the ENUM name server at Tier 2 level. (Alternatively the ENUM Subscriber may give this information directly to the

ENUM Tier 2 Nameserver Provider). The ENUM Registrar then asks the ENUM Tier 1 Registry to create NS records

for the ENUM Subscriber's ENUM domain name (associated with their assigned E.164 number) to point to the

nameserver that holds the NAPTR records. An ENUM User uses an ENUM Client, either directly or as part of an

ENUM enabled Application, to query the NAPTR records to find the information for the ENUM Subscriber with whom

they wish to communicate. After obtaining the NAPTR records the ENUM User or their application may use this

information to establish the communications between the ENUM User and the ENUM Subscriber.

An ENUM User may either use the ENUM Client directly or use an Application Client. The Application Client in turn

may either use the ENUM Client directly or forward the request to an Application Server, who may use an ENUM