ETSI TR 103 282 V1.1.1 (2014-07)

Network Technologies (NTECH); ENUM/ENUM-like options for Number Portability and actual use cases

DTR/NTECH-00004-NNAR-ENUM

General Information

• Status: Published
• Publication Date: 24-Jul-2014
• Technical Committee: NTECH - Network Technologies
• Current Stage: 12 - Completion
• Due Date: 31-Jul-2014
• Completion Date: 25-Jul-2014

Standards Content (Sample)

TECHNICAL REPORT
Network Technologies (NTECH);
ENUM/ENUM-like options for
Number Portability and actual use cases

2 ETSI TR 103 282 V1.1.1 (2014-07)

Reference
DTR/NTECH-00004-NNAR-ENUM
Keywords
DNS, enum, NP
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3 ETSI TR 103 282 V1.1.1 (2014-07)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 9
4 Basic concept of the present document . 9
4.1 Original meaning of ENUM and Number portability . 9
4.2 Background for ENUM-like mechanisms . 10
4.3 Incorporating NP mechanisms into ENUM-like mechanisms . 10
4.4 Actual use cases, studies by other SDOs or other organizations . 10
4.5 Target of the present document . 10
5 Options for number portability solution . 10
5.1 Overview . 10
5.2 No sharing of NPDBs among operators (Solution A) . 12
5.3 Mesh interconnection of NPDBs (Solution B) . 12
5.4 RefNPDB (Solution C) . 12
5.5 National OpDB (Solution D) . 12
5.6 Realtime Query of OpDB (Solution E) . 12
6 Possible options in terms of ENUM/ENUM-like solution for number portability . 13
6.1 Overview . 13
6.2 Local ENUM with no sharing of NP data among operators (NP/ENUM-option 1) . 15
6.3 Local ENUM with common/shared NP data among operators (NP/ENUM-option 2) . 15
6.4 National ENUM with collective NP data from all operators (NP/ENUM-option 3) . 15
6.5 Hierarchical ENUM (NP/ENUM-option 4). 16
7 Review on the new/old combination phase . 17
7.1 Example 1: Call routing/database lookup method employed during the new/old combination phase for
transition type "Solution C => Option 2" . 17
7.2 Example 2: Call routing/database lookup method employed during the new/old combination phase for
transition type "Solution A => Option 1" . 19
8 Conclusions . 20
Annex A: Conceptual overview of options for ENUM-like solution . 21
A.1 Procedure for creating options for ENUM-like solution based on actual use cases . 21
A.2 Documents to be referred . 21
A.2.1 TR 184 003 . 21
A.2.2 Recommendation ITU-T E.164 Supplement 2 . 22
A.2.3 GSMA IR.67 . 23
A.3 Creating conceptual overview of options for ENUM-like solution - 1 . 23
A.3.1 Establishing a correspondence between the use cases covered in TR 184 003 and the actual use cases in
the United States/the Netherlands . 23
A.3.2 Creating options for ENUM-like solution based on actual use cases in the United States/the Netherlands . 25
A.4 Creating conceptual overview of options for ENUM-like solution - 2 . 26
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4 ETSI TR 103 282 V1.1.1 (2014-07)
A.4.1 Establishing a correspondence between the use cases covered in TR 184 003 and GSMA IR.67 . 26
A.4.2 Creating options for ENUM-like solution based on use cases provided in GSMA IR.67 . 27
A.5 Creating conceptual overview of options for ENUM-like solution - 3 . 27
A.5.1 Creating options for ENUM-like solution based on a German ENUM implementation . 27
A.6 Existing options for establishing NP mechanisms and their corresponding options for establishing
ENUM-like mechanisms . 28
Annex B: Bibliography . 30
History . 31

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5 ETSI TR 103 282 V1.1.1 (2014-07)
Intellectual Property Rights
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
server (http://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.
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 "shall", "shall not", "should", "should not", "may", "may not", "need", "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 are usable inside DNS systems for routing
purposes, are currently 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 spent 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.
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).
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6 ETSI TR 103 282 V1.1.1 (2014-07)
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 in the world that are currently under implementation or are expected to be so in the near future.
2 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
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
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] ITU-T Supplement 2 to E.164 (2014): "Supplement 2: 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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7 ETSI TR 103 282 V1.1.1 (2014-07)
[i.11] Reference to a German ENUM implementation public information -e.g.
https://ripe64.ripe.net/presentations/93-e-wtklxc-RIPEGlobalVoix-003.pdf)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions 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 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 RFC 5067 [i.6] and technically based on 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 TR 184 003 [i.7]
Numbering Plan Administrator (NPA) DB: non-real time administrative data base that stores NPA Data
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8 ETSI TR 103 282 V1.1.1 (2014-07)
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 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 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 TR 184 003 [i.7].
operator: entity providing public telecommunications networks and/or public telecommunication services
NOTE: Source TR 184 003 [i.7].
ported number: number that has been subject to number portability
NOTE: Source TR 101 122 [i.1].
recipient network: current serving network where a number is located after being ported
NOTE: Source 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 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 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.
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9 ETSI TR 103 282 V1.1.1 (2014-07)
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACQ All Call Query
CD Call Dropback
CRDB Central Reference Data Base
DB Data Base
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
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
OP Operator
OpDB Operational Data Base
OR Onward Routeing
PLMN Public Land Mobile Network
QoR Query on Release
PSTN Public Switched Telephone Network
RefNPDB Reference Number Portability Data Base
SG Study Group
SIP Session Initiation Protocol
SIP-I SIP with encapsulated ISUP
SPP Service Provider Portability
TLD Top Level Domain
URI Uniform Resource Identifier
4 Basic concept of the present document
4.1 Original meaning of ENUM and Number portability
The ENUM system is defined and bound to a distributed, decentralized, hierarchical organization of numbers, in which
every provider makes available the numbers currently 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 can exist, 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.
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10 ETSI TR 103 282 V1.1.1 (2014-07)
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 system providing capabilities similar to those provided by the
standardized infrastructure ENUM. It should be noted that TR 184 003 [i.7] describes the opportunity to use also other
technologies than ENUM for providing NP in NGN mainly for coping with a very heterogeneous network environment.
4.3 Incorporating NP mechanisms into ENUM-like mechanisms
If ENUM or ENUM-like mechanisms are to be used as a tool for call establishment, giving adequate consideration for
number portability (NP) would be indispensable.
Since large investments towards NP implementation/operation have already been spent within each country, a
reasonable form of implementing ENUM-like mechanisms would be to implement them adhering to the existing NP
mechanisms varying from one country to another, based on the NP models and mechanisms that have been standardized
by ETSI and ITU-T.
4.4 Actual use cases, studies by other SDOs or other
organizations
For example, an ENUM-like mechanism applicable for NP operation is under development by a Dutch ENUM
implementation [i.9], based on an approach that utilizes the existing NP mechanism.
GSMA IR.67 [i.8], another example, sets out the different methods for establishing ENUM-like mechanism, depending
on whether the existing NP operation is based on a centralized database approach or a distributed database approach.
4.5 Target of the present document
Target of the present document is to organize and provide a conceptual overview of the available options for
implementing/establishing ENUM-like mechanisms, using as a basis the actual use cases (for instance a Dutch ENUM
implementation [i.9]) and studies undertaken by other organizations (for instance GSMA IR.67 [i.8]). Preferable options
for establishing ENUM-like mechanisms would be those by which existing NP mechanisms (already in operation within
each country) could be utilized to a maximum extent.
Each of the options is brought under review. Important items to be studied include issues related with the "co-
existence/combination" phase of the existing NP mechanism and the newly implemented ENUM-like mechanism.
5 Options for number portability solution
5.1 Overview
It is assumed that the selection of ENUM/ENUM-like mechanisms as required by the transition of networks to an all-IP
infrastructure, will indeed be significantly affected by the existing number portability solutions; in particular by the
previously adopted number portability database solutions. Based on this perspective, this clause aims to go over the
various options for number portability solution, using the below listed existing documents as source:
• TR 184 003 [i.7]; and
• Recommendation ITU-T E.164 Supplement 2 [i.2].
Figure 5.1, excerpted from Recommendation ITU-T E.164 Supplement 2 [i.2], provides a graphic explanation on the
examples of number portability database solution. All of the options shown in figure 5.1 maintain consistency with
TR 184 003 [i.7], in terms of terminology as well as concept.
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11 ETSI TR 103 282 V1.1.1 (2014-07)
NOTE: In some places the term "RefNPDB" is replaced with the term "CRDB".
Figure 5.1 is intended to cover the main number portability database solutions that are implemented in various countries
around the world.
Distributed solution Distributed solution
Applicable routing principles: OR, CD Applicable routing principles: QoR, ACQ
(Solution A) (Solution B)
Each operator's individual NP data is collected in each NP data from all operators is collected in each
operator's individual database (no sharing of NP data operator's individual database
between operators)
Non-real-time
NPDB NPDB NPDB Non-real-time
DBs
NPDB NPDB NPDB
DBs
Real-time DBs
OpDB OpDB OpDB
OpDB OpDB OpDB Real-time DBs
OP_A OP_B OP_C
OP_A OP_B OP_C
Centralized solution Distributed/centralized solution
Applicable routing principles: QoR, ACQ
(Solution C)
Applicable routing principles: QoR, ACQ
NP data from all operators is collected in a central non-real-time
database (CRDB); which will then be replicated to each operator's
individual database (opDB) to be queried for routing purposes
(Solution E)
Each operator's individual NP data is collected in each
CRDB
operator's individual database and can be reciprocally
queried in real-time
Non-real-time
NPDB NPDB NPDB
DBs
Non-real-time
OpDB OpDB OpDB Real-time DBs
NPDB NPDB NPDB
DBs
Real-time DBs
OP_A OP_B OP_C
(Solution D)
Pointer
NP data from all operators is collected in a central non-real-time DB
OpDB OpDB OpDB
database (CRDB); which will then be replicated to a central
real-time database to be queried for routing purposes (NOpDB)
OP_A OP_B OP_C
CRDB
Non-real-time
NPDB NPDB NPDB
DBs
Real-time DBs
OP_A OP_B OP_C
NOpDB
E.164 Suppl.2(12)_F13
Non-real-time database that is Real-time database that store NP data
used for storing NP data to be used for routing
Collection or replication of NP data DB query/response for routing purposes
OP_A Operator A
Figure 5.1: Examples of number portability database solution
(excerpted from Recommendation ITU-T E.164 Supplement 2 [i.2])
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12 ETSI TR 103 282 V1.1.1 (2014-07)
Of the five Solutions in figure 5.1 excerpted from Recommendation ITU-T E.164 Supplement 2 [i.2], Solution A, B,
and C are currently adopted in many countries as these Options are deployable on the legacy PSTN environment.
Solution D requires the implementation of a central real-time database (NopDB according to TR 184 003 [i.7]); in
which ensuring high reliability will become a major issue.
ENUM like technology can be used by the five Options in figure 5.1, especially in the case of Solution E, as a way of
implementing a NP database among other possible implementation Options, mainly in the context of NGN IP-based
network.
It should be noted that, Solution E is not listed in clause 6 among existing (currently adapted) options which has been
actually implemented for conventional PSTN/PLMN because Solution E is considered to be rather the solution for IP
networks (including NGN).
Additional explanations for each of the Solutions are shown in succeeding clauses.
5.2 No sharing of NPDBs among operators (Solution A)
In this option, each operator holds/manages a non-real-time database and a real-time database separately on its own.
Database management does not involve any transfer of database information between operators.
5.3 Mesh interconnection of NPDBs (Solution B)
In this option, NP data stored within each operator's individual non-real-time database (the NPDB according to
TR 184 003 [i.7]) are mutually exchanged between operators. This mutual exchange of number portability data
information enables each operator's individual non-real-time database and individual real-time database (the OpDB
according to TR 184 003 [i.7]) to hold NP data of all operators.
5.4 RefNPDB (Solution C)
In this option, a central non-real-time database is established to be shared by all the operators. NP data stored within
each operator's individual non-real-time database (NPDB) is transferred to this central non-real-time database
(RefNPDB); as a result the central non-real-time database will hold NP data from all operators. Each operator then
downloads data from this central non-real-time database, thereby enabling each operator's individual non-real-time
database (NPDB) and individual real-time database (OpDB) to hold NP data of all operators.
5.5 National OpDB (Solution D)
In this option, a central real-time database, together with a central non-real-time database, is established to be shared by
all the operators. NP data stored within each operator's individual non-real-time database is transferred to this central
non-real-time database; as a result the central non-real-time database will hold NP data from all operators. This data will
then be downloaded (from the central non-real-time database) to the central real-time database. Each operator directly
refers to this central real-time database in order to perform real-time processing.
5.6 Realtime Query of OpDB (Solution E)
In this option, each operator's individual NP data is collected in each operator's individual database (no sharing of NP
data between operators). However the operators are able to refer, in real-time, the NP data that is stored within each
operator's respective real-time databases (OpDB) by utilizing a DB query technology (e.g. ENUM like technology).
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13 ETSI TR 103 282 V1.1.1 (2014-07)
6 Possible options in terms of ENUM/ENUM-like
solution for number portability
6.1 Overview
Number portability has now for some time been operated within each country in accordance with the nationally
implemented number portability solution that is country-specific and thus varying from one country to another;
therefore it is conceivable that, in a country that has, for instance, implemented RefNPDB for number portability
operation, viable options for establishing ENUM/ENUM-like mechanisms will be designed on the premise of the
continuous utilization of this RefNPDB. On the contrary, for a country where RefNPDB has not been implemented for
number portability operation, it is highly likely that the options to be selected for establishing ENUM/ENUM-like
mechanisms will be based on a different approach without a RefNPDB. As can be seen in the above examples, it can be
assumed that ENUM/ENUM-like mechanisms as required by the transition of networks to an all-IP infrastructure (NGN
included), will indeed be significantly affected by the existing number portability solutions previously adopted within
each country.
Based on the above perspective, figure 6.1 provides a graphic summary of the different available options potentially
suitable for establishing ENUM/ENUM-like mechanisms. Detailed process of creating these options is provided in
Annex A of the present document. Each of the options, namely NP/ENUM-option 1, 2, 3, and 4, is brought under
review in clauses 6.2 to 6.5 respectively, in terms of general descriptions (placing focus on the methods for database
lookup/call routing).
It should be noted that, upon commercial implementation of the above new options, an intermediary phase, allowing for
a "co-existence/combination" of the new option implemented and the existing number portability solution, will
inevitably arise. In order to avoid causing operational hindrance to the number portability service and to ensure its
continuous availability for the end-users, it will be necessary to place under review the methods, employed during this
new/old combination phase, for performing database lookup and call routing between the new and old networks. A
review on some of the different patterns of this "co-existence/combination" is provided in clause 7.
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14 ETSI TR 103 282 V1.1.1 (2014-07)
Number portability solutions currently adopted
(Solution E is not listed here as an existing option )
Solution C Solution D
Solution A Solution B
No sharing of NPDBs Mesh interconnection
RefNPDB National OpDB (NOpDB)
among operators of NPDBs
Applicable routing principles: Applicable routing principles: Applicable routing principles: Applicable routing principles:
QoR, ACQ
OR, CD QoR, ACQ QoR, ACQ
NOp DB
Non
Non Ref NP DB
NPDB NPDB NPDB Real
Real
NPDB NPDB NPDB Non Ref NP DB
time
time Real
NPDB NPDB NPDB
time
Non
Real
OpDB OpDB OpDB
OpDB OpDB OpDB
Real NPDB NPDB NPDB Real
time
Real
OpDB OpDB OpDB
time
time
time
OP_A OP_B OP_C
OP_A OP_B OP_C
OP_B
OP_A OP_C
Real
OP_A OP_B OP_C
time
Entering “co-existence/combination” phase…
“Co-existence/combination” phase of newly implemented option and existing NP solution
(See the examples provided in Table 7.1, Figure 7.1, Table 7.2, and Figure 7.2)
End of “co-existence/combination” phase
Possible options for ENUM/ENUM-like solution corresponding to existing NP solutions
NP/ENUM-option 3
NP/ENUM-option 1
NP/ENUM-option 2
National ENUM with collective
Local ENUM with no sharing
Local ENUM with common/shared NP data among operators
NP data from all operators
of NP data among operators
Non
Non Ref NP DB
ENUM
Real
Real NPDB
NPDB
NPDB (National)
NPDB NPDB NPDB
time Non
time
Ref NP
Real
NPDB
Real DB
NPDB
time
NPDB
ENUM ENUM
Real
ENUM time
ENUM ENUM ENUM
(Local) Non
time (Local)
(Local) Real
(Local) (Local) (Local)
ENUM Real
OP_C NPDB NPDB NPDB
time
ENUM
OP_A OP_B
OP_A OP_B OP_C ENUM
(Local) time
(Local)
(Local)
OP_C
Real
OP_A
[Routing method-1] OP_B
OP_A OP_B OP_C
time
[Routing method]
Donor NW
Originating
Recipient
NPD of All Operators
NW [Routing method]
NAPTR
NW
(non-ENUM data)
NPD of All Operators
ENUM Query/response
(non-ENUM data)
Originating
Termi- Donor
NW
Origi- NAPTR Recipient
nating NW
nating
NW
ENUM Query/response
NAPTR of All
Operators
Termi-
[Routing method-2]
Origi-
nating
Recipient NW
nating
Originating
Donor NW
Originating
NW
Donor
NW
NW
NS Recipient
NAPTR
ENUM Query/response NW
ENUM Query/response
ENUM Query/response
Termi-
Origi-
Origi- Termi-
nating
nating
nating nating
NP/ENUM-option 4
Hierarchical ENUM
[Routing method]
ENUM
(Tier-1)
ENUM
NS of All
RefNP Real
(Tier-1) Operators
DB time
Real
time
Non Non Originating
NPDB NW
Real Donor
Real
NPDB Recipient NW
NPDB NPDB NPDB
NPDB
NW
time time
NAPTR
ENUM Query/response
Real
Real
ENUM
ENUM ENUM
time
ENUM time ENUM
(Tier-2)
ENUM Query/response
ENUM (Tier-2)
(Tier-2l)
(Tier-2l)
(Tier-2) Origi- Termi-
(Tier-2) OP_C
OP_A nating nating
OP_B
OP_A OP_C
OP_B
NOTE: The Donor network is not needed as a transit network for the signalling path.

Figure 6.1: Examples of ENUM/ENUM-like solution for number portability
ETSI
15 ETSI TR 103 282 V1.1.1 (2014-07)
6.2 Local ENUM with no sharing of NP data among operators
(NP/ENUM-option 1)
In this option, each operator holds/manages a non-real-time database (NPDB) and a real-time Local ENUM database
separately on its own. Database management does not involve any transfer of database information between the
operators: that is, NP data stored within each operator's NPDB are converted to ENUM NAPTR records and stored in
the Local ENUM database of each operator.
When a subscriber of the Donor network (i.e. the number range holder) ports out to another (i.e. the Recipient) network,
the domain name in the URI/URL for the ported-out subscriber, stored within the Local ENUM database of the Donor
operator, will be modified to show the NP data of the ported-out subscriber. The host part of the URI/URL will contain
a DNS domain which is assigned to the recipient network.
As for call routing, there are a few possible methods, including the following two:
1) Routing method Example 1 (NP/ENUM-option 1-1)
NAPTR record of the porting subscriber is stored within the database of the Donor network (i.e. the number
range holder).
For call routing, the Originating network will query the Local ENUM database of the Donor network (i.e. the
number range holder) in order to obtain NP data of the porting subscriber.
2) Routing method Example 2 (NP/ENUM-option 1-2)
NAPTR record of the porting subscriber is stored within the database of the Recipient network. In addition to
this, an NS record pointing to the ENUM server of the Recipient network will be stored within the database of
the Donor network (i.e. the number range holder).
For call routing, the Originating network firstly queries the Local ENUM database of the Donor network
(i.e. the number range holder), and then using the pointer information obtained from this query, secondly
queries the Local ENUM database of the Recipient network in order to obtain NP data of the porting
subscriber.
This option would be more suitable for countries whose existing number portability solutions are based on not
sharing NPDB among operators (Option A).
6.3 Local ENUM with common/shared NP data among
operators (NP/ENUM-option 2)
In this option, NP data regarding all the operators are stored within each operator's individual non-real-time database
(NPDB). This is made possible either by:
i) each operator downloading data from the central non-real-time database (RefNPDB), or by
ii) mutual exchange of database information between each operator's decentralized individual non-real-time
database (NPDB).
NP data (regarding all operators) stored within each operator's NPDB are converted to ENUM NAPTR records
(regarding all operators) and stored in the Local ENUM database of each operator.
For call routing, the Originating network will query its own Local ENUM database in order to obtain NP data of the
porting subscriber.
This option would be more suitable for countries whose existing number portability solutions are based on the
utilization of RefNPDB/CRDB or mesh interconnection of NPDBs.
6.4 National ENUM with collective NP data from all operators
(NP/ENUM-option 3)
In this option, a National ENUM database, together with a central non-real-time database (RefNPDB), is established to
be shared by all the operators. NP data stored within each operator's individual non-real-time database is transferred to
the RefNPDB; as a result the RefNPDB will hold NP data regarding all the operators. NP data (regarding all operators)
stored within the RefNPDB are converted to ENUM NAPTR records (regarding all operators) and stored in the
National ENUM database.
ETSI
16 ETSI TR 103 282 V1.1.1 (2014-07)
For call routing, each operator directly queries this National ENUM database in order to perform real-time processing.
This option would be more suitable for countries whose existing number portability solutions are based on the
utilization of central NP databases.
6.5 Hierarchical ENUM (NP/ENUM-option 4)
In this option, hierarchical architecture is adopted for the ENUM database: that is, Tier-2 ENUM databases are
established on the operator level and a Tier-1 ENUM database is established on the national level.
Each operator holds/manages a non-real-time database (NPDB) and a real-time Tier-2 ENUM database separately on its
own. NP data stored within each operator's NPDB are converted to ENUM NAPTR records and stored in the Tier-2
ENUM database of each operator.
In addition to this, a Tier-1 ENUM database is established on the national level to be shared by all the operators. NS
records pointing to Recipient networks will be stored within this Tier-1 ENUM database.
When a subscriber of an operator ports out to another (i.e. the Recipient) operator, this Recipient operator will create an
NAPTR record of the ported-in subscriber and store it within its Tier-2 ENUM database. At the same time, an NS
record pointing to the Recipient network will be created within the Tier-1 ENUM database.
For call routing, the Originating network firstly queries the Tier-1 ENUM database, and then using the pointer
information obtained from this query, secondly queries the Tier-2 ENUM database of the Recipient operator in order to
obtain NP data of the porting subscriber.
This option woul
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