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TECHNICAL REPORT
Network Technologies (NTECH);
Options for Number Portability and actual use cases
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2 ETSI TR 103 282 V2.1.1 (2019-05)
Reference
RTR/NTECH-0040
Keywords
DNS, enum, NP
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3 ETSI TR 103 282 V2.1.1 (2019-05)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 10
3.3 Abbreviations . 10
4 Basic concept of the present document . 11
4.1 Original meaning of ENUM and Number portability . 11
4.2 Background for ENUM-like mechanisms . 11
4.3 Incorporating NP mechanisms into ENUM-like mechanisms . 11
4.4 Actual use cases, studies by other SDOs or other organizations . 11
4.5 Target of the present document . 12
5 Options for number portability solution . 12
5.1 Overview . 12
5.2 No sharing of NPDBs among operators (Solution A) . 14
5.3 Mesh interconnection of NPDBs (Solution B) . 14
5.4 RefNPDB (Solution C) . 14
5.5 National OpDB (Solution D) . 14
5.6 Realtime Query of OpDB (Solution E) . 14
6 Possible options in terms of ENUM/ENUM-like solution for number portability . 15
6.1 Overview . 15
6.2 Local ENUM with no sharing of NP data among operators (NP/ENUM-option 1) . 17
6.3 Local ENUM with common/shared NP data among operators (NP/ENUM-option 2) . 17
6.4 National ENUM with collective NP data from all operators (NP/ENUM-option 3) . 17
6.5 Hierarchical ENUM (NP/ENUM-option 4). 18
7 Review on the new/old combination phase . 19
7.0 General . 19
7.1 Example 1: Call routing/database lookup method employed during the new/old combination phase for
transition type "Solution C => Option 2" . 19
7.2 Example 2: Call routing/database lookup method employed during the new/old combination phase for
transition type "Solution A => Option 1" . 21
8 Conclusions . 22
Annex A: Conceptual overview of options for ENUM-like solution . 23
A.1 Procedure for creating options for ENUM-like solution based on actual use cases . 23
A.2 Documents to be referred . 23
A.2.1 ETSI TR 184 003 . 23
A.2.2 Recommendation ITU-T E.164 Supplement 2 . 24
A.2.3 GSMA IR.67 . 25
A.3 Creating conceptual overview of options for ENUM-like solution - 1 . 25
A.3.1 Establishing a correspondence between the use cases covered in ETSI TR 184 003 and the actual use
cases in the United States/the Netherlands . 25
A.3.2 Creating options for ENUM-like solution based on actual use cases in the United States/the Netherlands . 27
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4 ETSI TR 103 282 V2.1.1 (2019-05)
A.4 Creating conceptual overview of options for ENUM-like solution - 2 . 28
A.4.1 Establishing a correspondence between the use cases covered in ETSI TR 184 003 and GSMA IR.67 . 28
A.4.2 Creating options for ENUM-like solution based on use cases provided in GSMA IR.67 . 29
A.5 Creating conceptual overview of options for ENUM-like solution - 3 . 29
A.5.1 Creating options for ENUM-like solution based on a German ENUM implementation . 29
A.6 Existing options for establishing NP mechanisms and their corresponding options for establishing
ENUM-like mechanisms . 30
Annex B: Several Use cases of Number Portability toward all IP . 32
B.1 Use Case in Japan [ENUM-like] . 32
B.2 Use Case in the United States [non-ENUM like] . 33
B.3 Use Case in the Netherlands [Both non-ENUM-like and ENUM-like could be used optionally] . 34
B.4 Use Case in Italy [non-ENUM like] . 37
B.5 Use Case in Switzerland [non-ENUM like] . 38
B.6 Use Case in Sweden [non-ENUM like] . 39
B.7 Use Case in Finland [ENUM-like is foreseen] . 40
Annex C: Bibliography . 42
History . 43
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5 ETSI TR 103 282 V2.1.1 (2019-05)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables 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
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Network Technologies (NTECH).
Some material contained herein is the copyright of, or has been supplied by ITU-T.
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
In voice and multimedia IP-based networks (NGN included), E.164 numbers are, and will continue to be used as the
basic (primary) identifier that enables the originating party to establish a call/communication with an end-user or a
service. In this context, infrastructure ENUM systems, being an effective mechanism for mapping E.164 numbers to
URIs, that identify the network actually serving these E.164 numbers and that are usable inside DNS systems for
routing purposes, are at the time of writing being implemented inside networks, or are expected to be implemented at
some point in the near future.
On the other hand number portability (NP), has now for some time operated within each country based on standard
technical solutions (usually NP mechanisms defined by ITU-T and ETSI on traditional telephone technology),
nationally adapted and implemented with country-specific characteristics. Since large investments towards
implementing and operating number portability have already been done by the telecommunications operators within
each country, and typically such NP solutions work, it is likely that the options to be selected for establishing ENUM
mechanisms will be based on safeguarding the national investments already done, following progressive network
technological evolutions towards NGN.
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6 ETSI TR 103 282 V2.1.1 (2019-05)
So it can be assumed that ENUM mechanisms, when used inside NGN IP-based networks, will in principle conform
with the existing national number portability solutions already adopted and working within each country; therefore there
will be a number of different options suitable for establishing ENUM mechanisms without necessarily changing or
evolving existing NP technical solutions. It is important to remark that ENUM is, first of all, a hierarchical system that
extends the DNS system, following in principle the same approach, and ENUM is also a standard "query" protocol to
derive, based on E.164 numbers, the appropriate routing information, that is usable inside IP-based networks. These
ENUM components are part of the ENUM system, also in the case of ENUM query mechanisms implemented inside
existing NP solutions (referred as ENUM-like non-standard solutions).
Although around five years have passed since the first version of the present document was published in June 2014, in
most countries, migration from PSTN to IP-based networks (NGN included) is not complete yet. This revised version
introduces actual use cases of number portability in 7 countries towards all IP networks in order to verify the estimated
direction of number portability described in the original version, which was expected to be "ENUM-like" technology
with considerable degrees of variation among the possible solutions.
The present document introduces several use cases of current or proposed number portability solutions at this point
toward all IP in 7 countries (Japan, US, Netherlands, Italy, Switzerland, Sweden, Finland) with the cooperation of
experts from each country. They are newly described in Annex B.
Although these use cases may include indecisive area it can be said that there are other options than ENUM-like
technology concerning all IP Number Portability so that the ENUM-based option may not necessarily be the target for
some networks or countries.
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7 ETSI TR 103 282 V2.1.1 (2019-05)
1 Scope
The present document aims to lay out and organize the various available options for establishing ENUM or ENUM-like
mechanisms for number portability, and to establish a correspondence between these available options and actual use
cases that are currently under implementation or are expected to be so in the near future.
Also the present document introduces several use cases of current or proposed number portability solutions at this point
toward all IP in 7 countries (Japan, US, Netherlands, Italy, Switzerland, Sweden, Finland) with the cooperation of
experts from each country. They are newly described in Annex B in the revised version.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TR 101 122 (V1.1.1): "Network Aspects (NA); Numbering and addressing for Number
Portability".
[i.2] Recommendation ITU-T E.164 Supplement 2 (2014): "Number portability".
[i.3] Recommendation ITU-T E.101 (2009): "Definitions of terms used for identifiers (names, numbers,
addresses and other identifiers) for public telecommunication services and networks in the E-series
Recommendation".
[i.4] IETF RFC 6116: "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation
Discovery System (DDDS) Application (ENUM)".
[i.5] Recommendation ITU-T E.164 (2010): "The international public telecommunication numbering
plan".
[i.6] IETF RFC 5067: "Infrastructure ENUM Requirements".
[i.7] ETSI TR 184 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Portability of telephone numbers between operators for Next
Generation Networks (NGNs)".
[i.8] GSMA IR.67 version 8.0 (23 November 2012): "DNS/ENUM Guidelines for Service Providers &
GRX/IPX Providers".
[i.9] Reference to a Dutch ENUM implementation public information.
(e.g.: https://www.coin.nl/index.php/en/).
[i.10] Reference to a North American ENUM implementation public information.
(e.g.: http://www.itu.int/ITU-D/finance/work-cost-tariffs/events/tariff-seminars/Geneva-
OriginID/pdf/Session2_Lind_ENUM_presentation.pdf).
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8 ETSI TR 103 282 V2.1.1 (2019-05)
[i.11] Reference to a German ENUM implementation public information.
(e.g. https://ripe64.ripe.net/presentations/93-e-wtklxc-RIPEGlobalVoix-003.pdf).
[i.12] GSMA NG.105 ENUM Guidelines for Service Providers and IPX Providers.
[i.13] TTC standard JJ-90.31-v3: "Common interconnection interface for carrier ENUM".
[i.14] TTC standard JT-E164_Supplement_2: "Number Portability".
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
data base query function: function whereby a data base is accessed in order to ascertain whether a telephone number
is ported, and if it is, a Routeing Number or a domain name is obtained that can be used to route the call to a destination
donating network: network from which the number has been ported out in the last porting process
donor network: initial network where a number was allocated by the Numbering Plan Administrator before ever being
ported
NOTE: Source ETSI TR 101 122 [i.1].
E.164 number: A string of decimal digits that satisfies the three characteristics of structure, number length and
uniqueness specified in Recommendation ITU-T E.164 [i.5]. The number contains the information necessary to route
the call to the end user or to a point where a service is provided.
NOTE: Source Recommendation ITU-T E.101 [i.3].
ENUM data: data for mapping an E.164 number to an URI
NOTE: Mapping can be done directly or by providing pointers to other ENUM DBs according to ordinary DNS
procedures.
ENUM system: real time hierarchical and distributed system that stores ENUM data and used to resolve E.164
numbers to URIs at session initiation
ENUM query: query adhering to the ENUM query protocol in order to resolve a specific E.164 number to a domain
name for routing purposes (e.g. a routable URI)
infrastructure ENUM: ENUM system defined in IETF RFC 5067 [i.6] and technically based on IETF RFC 6116 [i.4]
NOTE: The infrastructure ENUM is defined and used only inside a network and among networks for routing
purposes.
Location portability: ability of an end user to retain the same telephone number when moving from one location to
another, without changing his service provider
NP Routing Information (NPRI): information needed to complete a communication request to a ported telephone
number
Numbering Plan Administrator (NPA) data: off-line data published by the Numbering Plan Administrator (NPA)
which provide the number block assignments to operators that provide services within the jurisdiction of the NPA
NOTE 1: If the telephone numbers are subject to number portability the actual operator serving a specific telephone
number can differ from the one provided by these data, if these data are not kept aligned with NP data. In
cases where telephone numbers are assigned directly to end users, the operator chosen by the end user to
provide services is due to spread information that he is serving that telephone number.
NOTE 2: Source ETSI TR 184 003 [i.7].
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9 ETSI TR 103 282 V2.1.1 (2019-05)
Numbering Plan Administrator (NPA) DB: non-real time administrative data base that stores NPA Data
Number Portability Data (NPD): off-line data linked to ported telephone numbers as they are stored in and retrieved
from the NPDB
NOTE 1: This data consist of a list of ported telephone numbers with associated domain names or routeing numbers
and optionally further information of traffic and/or administrative nature. Normally these data are
provided in a format which requests for further processing in order to render routeing information.
NOTE 2: Source ETSI TR 184 003 [i.7].
Number Portability Data Base (NPDB): non-real time data base that is used to store NP Data
NOTE 1: As an option the NPDB may contain information for all telephone numbers (i.e. also non-ported
telephone numbers). Such additional information would be based on NPA Data.
NOTE 2: Source ETSI TR 184 003 [i.7].
Number Portability (NP) query: query function whereby a data base is accessed in order to ascertain whether a
telephone number is ported, and if it is, a Routeing Number or a domain name is obtained that can be used to route the
call to a destination
Operational Data Base (OpDB): real time data base that store data from the NPDB to be transformed to NRI used for
routing
NOTE: Source ETSI TR 184 003 [i.7].
operator: entity providing public telecommunications networks and/or public telecommunication services
NOTE: Source ETSI TR 184 003 [i.7].
ported number: number that has been subject to number portability
NOTE: Source ETSI TR 101 122 [i.1].
recipient network: current serving network where a number is located after being ported
NOTE: Source ETSI TR 101 122 [i.1].
Reference Number Portability Data Base (RefNPDB): non-real time reference NPDB
NOTE 1: It is national matter whether there is one physical RefNPDB or a logical one, which may be distributed
over the operators involved.
NOTE 2: Source ETSI TR 184 003 [i.7].
NOTE 3: In some places the term "RefNPDB" is replaced with the term "CRDB".
service portability: ability of an end user to retain the same telephone number when changing from one type of service
to another
Service Provider Portability (SPP): ability of an end user to retain the same telephone number when changing from
one service provider to another
NOTE: Source ETSI TR 184 003 [i.7].
telephone number; directory number: number adhering to the national E.164 numbering plan, used by the originating
party to establish a call/communication to an end user or a service
NOTE: Source Recommendation ITU-T E.101 [i.3]. The E.101 definition has been modified here to be
independent of the network technology, e.g. NGN, PSTN/ISDN and other technologies. The E.101
original definition is:
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10 ETSI TR 103 282 V2.1.1 (2019-05)
"4.22 telephone number; phone number; directory number (DN): The number, derived from the E.164
numbering plan, used by the calling party to establish a call to an end user or a service.
The number may also be used for presentation services like calling line identification presentation (CLIP)
and connected line identification presentation (COLP) and may also be published in different directories
and/or directory enquiry services".
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACQ All Call Query
CD Call Dropback
CLIP Calling Line Identification Presentation
COLP Connected Line Identification Presentation
CRDB Central Reference Data Base
DB Data Base
DN Directory Number
DNS Domain Name System
ENUM tElephone NUMber mapping
GSMA Global System For Mobile Communications Association
IETF Internet Engineering Task Force
IMS IP Multimedia Subsystem
IP Internet Protocol
IPX Internet Packet eXchange
ISDN Integrated Services Digital Network
ISUP ISDN User Part
NAPTR Naming Authority Pointer
NGN Next Generation Network
NopDB National Operational Data Base
NP Number Portability
NPA Numbering Plan Administrator
NPD NP Data
NPDB Number Portability Data Base
NPRI NP Routing Information
NS Name Server
NW Network
OP Operator
OpDB Operational Data Base
OR Onward Routeing
PLMN Public Land Mobile Network
PSTN Public Switched Telephone Network
QoR Query on Release
RefNPDB Reference Number Portability Data Base
SG Study Group
SIP Session Initiation Protocol
SIP-I SIP with encapsulated ISUP
SNPAC Sweden Number Portability Administrative Center
SPP Service Provider Portability
TLD Top Level Domain
TTC Telecommunication Technology Committee
URI Uniform Resource Identifier
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4 Basic concept of the present document
4.1 Original meaning of ENUM and Number portability
The ENUM system is defined as bound to a distributed, decentralized, hierarchical organization of numbers, in which
every provider makes available the numbers, at the time of writing handled, in principle, through a local ENUM system
that is part of an infrastructure ENUM hierarchy.
On the one hand if a Central Reference Data Base exists, it is not in principle involved in the real-time handling of the
calls, but it can be used as a national repository. For this reason this Administrative Central Reference Data Base is
considered technically distinct from the ENUM system; in addition it will not in principle be a pre-requisite for the
ENUM system implementation and will not influence nor change the intrinsic characteristics of the ENUM system
itself, which is defined in international and ETSI normative and technical specifications.
Thus it is not a requirement for the ENUM implementation to change or evolve existing NP models, since the
infrastructure ENUM system can be just integrated inside existing NP solutions; in other cases the ENUM system
implementation at national level can deeply impact or change existing NP solutions.
4.2 Background for ENUM-like mechanisms
In IP-based networks telephone numbers are still being used as the basic (primary) identifier. In this context ENUM
mechanisms are currently being implemented, or are expected to be implemented at some point in the near future, as a
tool for mapping E.164 numbers to URIs. With ENUM system in the present document it is referred only the case of the
infrastructure ENUM [i.6]; as a consequence, it uses a "technical" TLD other than the "e164.arpa", which is used for
public or User ENUM. An ENUM-like system is a sy
...