SIST EN 301 160 V1.2.1:2005

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Usmerjanje klicev do storitev evropskega telefonskega številskega prostora (ETNS)Routeing of calls to European Telephony Numbering Space (ETNS) services33.040.35Telefonska omrežjaTelephone networksICS:Ta slovenski standard je istoveten z:EN 301 160 Version 1.2.1SIST EN 301 160 V1.2.1:2005en01-januar-2005SIST EN 301 160 V1.2.1:2005SLOVENSKI
STANDARD
ETSI ETSI EN 301 160 V1.2.1 (2002-01)2
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ETSI ETSI EN 301 160 V1.2.1 (2002-01)3 Contents Intellectual Property Rights.5 Foreword.5 1 Scope.6 2 References.6 3 Definitions, symbols and abbreviations.6 3.1 Definitions.6 3.2 Symbols.8 3.3 Abbreviations.8 4 Reference model for the ETNS.9 4.1 Call-related (Routeing Part).10 4.1.1 Getting the ETNS Routeing number (Rn).10 4.1.2 Providing the ETNS service.10 4.1.3 Examples of Call Handling.10 4.2 Non-call related (Management part).11 4.2.1 ETNS number assignment.11 4.2.2 Obtaining Routeing numbers (Rns).11 4.2.3 Distribution of ETNS Routeing numbers (Rns).11 5 Routeing.12 5.1 Routeing methods.12 5.1.1 Single translation.12 5.1.2 Double translation.13 5.2 Structure of ETNS Routeing numbers.14 5.3 Addressing between networks.14 6 Number portability within the ETNS.15 Annex A (Informative): Routeing of calls to corporate networks (CN).16 A.1 Model for actors involved.16 A.2 Routeing methods.16 A.2.1 Double translation.17 A.2.1.1 Example 1: SgN and ScN located in different countries and 2 access points into the CN.17 A.2.1.2 Example 2: SgN and ScN located in different countries and 1 access point into the CN.18 A.2.1.3 Example 3: SgN and ScN located in 1 country and 2 access points into the CN.19 A.2.1.4 Example 4: SgN and ScN located in 1 country and 1 access point into the CN.20 A.2.2 Single translation.20 A.2.2.1 Case 1: SgN/ScN located in another country than the CN and 2 access points into the CN.21 A.2.2.2 Case 2: SgN/ScN located in another country than the CN and 1 access point into the CN.21 A.2.2.3 Case 3: SgN/ScN located in the same country as CN and 2 access points into the CN.22 A.2.2.4 Case 4: SgN/ScN located in the same country as CN and 1 access point into the CN.23 A.2.3 Direct routeing.23 A.3 Necessary digit analysis.24 Annex B (informative): Structures of the ETNS Routeing numbers.25 B.1 Structures of the ETNS Routeing numbers.25 B.1.1 Choice of Structure.25 B.2 Comparison of the 2 alternatives for routeing numbers (Rns): National specific Rns and Network specific Rns.26 B.2.1 National specific Rns:.26 B.2.2 Network specific Rns.28 Annex C (informative): Impact of Routeing on Signalling.30 SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)4 C.1 General Implications.30 C.2 Rn1 Routeing method.31 C.3 Rn2 Routeing method.31 C.3.1 Introduction.31 C.3.2 E.164 number as Rn for routeing to service network.31 C.3.3 NRN as Rn for routeing to service network.32 C.3.4 Use of the ISUP procedures for GVNS.32 C.3.5 Support of E.353 for INRA.32 C.4 Implications of SCCP routeing.33 C.5 Summary.33 Annex D (informative): Bibliography.34 History.35
ETSI ETSI EN 301 160 V1.2.1 (2002-01)5 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://webapp.etsi.org/IPR/home.asp). 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 European Standard (Telecommunications series) has been produced by ETSI Technical Committee Services and Protocols for Advanced Networks (SPAN).
National transposition dates Date of adoption of this EN: 18 January 2002 Date of latest announcement of this EN (doa): 30 April 2002 Date of latest publication of new National Standard or endorsement of this EN (dop/e):
31 October 2002 Date of withdrawal of any conflicting National Standard (dow): 31 October 2002
ETSI ETSI EN 301 160 V1.2.1 (2002-01)6 1 Scope The present document specifies the routeing methods that shall be used for implementation of the European Telephony Numbering Space (ETNS), the alternative structures of the routeing numbers and the addressing between networks. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication and/or edition number or version number) or non-specific. • For a specific reference, subsequent revisions do not apply. • For a non-specific reference, the latest version applies. [1] ETSI EN 301 161 (V1.1.1): "Management of the European Telephony Numbering Space (ETNS)". [2] ETSI EN 301 070-1 (V1.2.2): "Integrated Services Digital Network (ISDN); Signalling System No.7; ISDN User Part (ISUP) version 3 interactions with the Intelligent Network Application Part (INAP); Part 1: Protocol specification [ITU-T Recommendation Q.1600 (1997), modified]". [3] ETSI EN 301 464 (V1.1.1): "Integrated Services Digital Network (ISDN); Signalling System No.7 (SS7); ISDN User Part (ISUP) version 4 interactions with the Intelligent Network Application Part (INAP); Part 1: Protocol specification [ITU-T Recommendation Q.1601 (1999), modified]". [4] ETSI TR 101 092: "Network Aspects (NA); Report on Carrier Selection". [5] ETSI ETS 300 121: "Integrated Services Digital Network (ISDN); Application of the ISDN User Part (ISUP) of CCITT Signalling System No.7 for international ISDN interconnections (ISUP version 1)". [6] ETSI EN 300 356-1 (V4.2.1): "Integrated Services Digital Network (ISDN); Signalling System No.7 (SS7); ISDN User Part (ISUP) version 4 for the international interface; Part 1: Basic services [ITU-T Recommendations Q.761 to Q.764 (1999) modified]". [7] ETO Report: "Management, Routeing and Portability aspects of the European Telephony Numbering Space (ETNS)". [8] ITU-T Recommendation E.164: "The international public telecommunication numbering plan". [9] ITU-T Recommendation E.353: "Routing of calls when using international routing addresses". [10] ITU-T Recommendation Q.767: "Application of the ISDN user part of CCITT signalling system No. 7 for international ISDN interconnections". 3 Definitions, symbols and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: administrator: has the responsibility for the high level management of the ETNS assisted network: network which routes a call to an ETNS number towards a serving network it has agreement with in order to complete the call SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)7 called party: entity that terminates a call to an ETNS number calling party: entity that dials an ETNS number ETNS country: CEPT member country participating in the ETNS ETNS number: number from the ETNS numbering resource ETNS registrar database: database maintained by the registrar where all data, both administrative and operational, for each ETNS number are registered ETNS signalling address: standardized address used to route signalling messages over the interface, that is not in the call path, between any pair of ETNS entities NOTE: An example may be the use of SCCP Global Titles. ETNS routeing number: ITU-T Recommendation E.164 number used to route to the service exchange NOTE: It can also identify the called party, the ETNS service provider/producer, and/or the originating network. ITU-T Recommendation E.353 is an alternative in the future. ETNS service producer: functional entity producing the ETNS service(s) in question, having real-time control of the service(s) ETNS service provider: functional entity that provides one or more ETNS service(s) to its ETNS subscribers on a contractual basis and is not involved in real-time control of the service NOTE: See clause 4 for the relationship between service producer and service provider. ETNS service: service that has been assigned a European Service Identity (ESI) ETNS subscriber: entity that requests a ETNS number from a ETNS service provider in order to offer access from a calling party to a ETNS service ETNS translation database: capability, which in the call process, translates the ETNS number into a routeing number ETNS: numbering resource identified by ITU-T Recommendation E.164 country code 388 and a one digit identification code whose current value is 3, used for the provisioning of the ETNS services originating network: network, either assisted or serving, to which the calling party is connected registrar: responsible for the day-to-day management of the European Service Numbers (ESNs) behind each ESI service exchange: exchange of the service network that triggers the provision of the service on reception of the routeing number, and then forwards the call service network: network that operates one or more service exchange(s) serving exchange: exchange, in the serving network, that can interrogate directly or indirectly an ETNS translation database to obtain a routeing number related to the ETNS number, and then forwards the call to the service network serving network: network, with one or more serving exchanges terminating number: number containing explicit information on the terminating point of the called party NOTE: The number is used to route towards the called party. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)8 3.2 Symbols For the purposes of the present document, the following symbols apply:
called party (symbol needs to correspond to figure)
calling party
combined serving and service exchange
ETNS service provider database
ETNS translation database
originating, transit or destination exchange
service exchange
serving exchange 3.3 Abbreviations For the purposes of the present document, the following abbreviations apply: AN Assisted Network CC ITU-T Recommendation E.164 Country Code CEPT European Conference of Postal and Telecommunications Administrations
CN Corporate Network CNID Corporate Network IDentity CNSN Corporate Network Subscriber Number CS Connected Subaddress
DR Direct Routeing DT Double Translation En ETNS number ESI European Service Identity ESNs European Service Numbers
ETNS European Telephony Numbering Space GVNS Global Virtual Network Service
IN Intelligent Network INAP Intelligent Network Application Protocol INRAs International Network Routeing Adresses
ISDN Integrated Services Digital Network
ISUP ISDN User Part NDC National Destination Code identifying the Rn series of addresses NDCx National Destination Code identifying a series of terminating numbers in country x NN National Numbers
NNA National Numbering Authority NNR National Number Resource NoA Nature of Address
NP Numbering Plan
RA Routeing Address Rn Routeing number RNIC Routeing Number Identification Code SA Signalling Address
SC Signalling Capability SCCP Signalling Connection Control Part ScN Service Network SD Subsequent Digits SgN Serving Network SN Subscriber Numbers within the Rn series of addresses SNIC Service Network Identification Code SNx Subscriber Numbers within the Tn series of numbers in country x SS7 Signalling System N°7
ST Single Translation SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)9 TN Terminating Network Tn Terminating number TrN Transit Network VLR Visitor Location Register (GSM)
4 Reference model for the ETNS This clause provides a conceptual description of the implementation of the European Telephony Numbering Space (ETNS). Figure 1 shows the actors involved in the ETNS, and their relationship with each other. Also shown in figure 1 are the relevant reference points for the ETNS that are described in clauses 4.1 and 4.2. Figure 1 is divided into call-related and non-call-related parts in order to clearly show the distinction between the routeing functions and the management functions.
Service Producer ETNS Assisted
Network
Serving
Network
Calling
Party
Service
Network
Terminating
Network
Called
Party
Registrar
ETNS Subscriber
Administrator
E
D
B
C
F
A
NON-CALL-RELATED [MANAGEMENT PART]
CALL-RELATED [ROUTEING PART]
Service Provider ETNS ETNS
Translation G
ETNS Translation Service
Producer ETNS Service Network NNA
Figure 1: Actors and reference points The reference points in the call-related part of figure 1 are used in the present document, while the reference points in the non call-related part are used in EN 301 161 [1]. For simplicity transit networks are not shown in figure 1, but these could be present between any of the networks. The ETNS Service Provider is the entity that is relevant in the process of number assignment. The service producer and service network are entities that are relevant in call processing. The ETNS Service Provider, ETNS Service Producer and the service network may or may not be a single legal entity. Such a distinction leads to the recognition of two concepts under the term "service provision":
• the function of the first is to sell a service to an ETNS subscriber, and to be the sole interface with this ETNS subscriber. This is the role of the ETNS Service Provider; • the function of the second is to operate the call. This is the role of the ETNS Service Producer and the service network. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)10 The Serving Network (SgN) is responsible for routeing a call from the calling party to the service network. The service network participates through the service exchange in the provision of ETNS services.
ETNS numbers are managed by an independent body, identified as the registrar and administrator in figure 1. 4.1 Call-related (Routeing Part) This clause describes the principles for routeing a call from the calling party to the called party. A call to an ETNS number (En) can be divided in two parts. 4.1.1 Getting the ETNS Routeing number (Rn) The calling party shall dial the En in its international format. Based on the ESI [1], the call is routed to the serving exchange in the SgN. Potentially, this exchange may not be located in the calling party's network. The originating network is then called an assisted network, interconnected to the SgN through reference point C. An assisted network can be connected to multiple SgNs. The serving exchange, analysing the ESI, triggers the ETNS translation database using the incoming En to derive an outgoing ETNS Routeing Number or ETNS signalling address. The ETNS translation database can be inside or outside the SgN. Several SgNs may share the same ETNS translation database. The Routeing information from one En can vary from one SgN to another. When the SgN and the ScN are the same, the serving and service exchange within the network can be the same, and reference point B in figure 1 will then be internal.
4.1.2 Providing the ETNS service The proceeding of the call set up in the service network and beyond depends on the nature of the service on the one side, and on the relationship between the ETNS Service Producer and the service network on the other side. The nature of the service will determine the path of the call.
The relationship between the ETNS Service Producer and the service network will determine the responsibilities of each actor as regards service provision. The two actors can be the same entity which operates the service, or the ETNS Service Producer can rely upon the telecommunication infrastructure of a different service network and only operate e.g. a database when a double translation is required, see clause 5. The implementation of reference point "A" between the service network and the Service Producer depends on the service, technical constraints and the requirements from the regulatory environment. 4.1.3 Examples of Call Handling Figure 2 shows some examples of call handling. The examples show simplified network diagrams where the Calling Party is shown as directly connected to the Serving Network and the Called Party is connected to the Service Network. In practice an Assisted Network could separate the Calling Party from the Serving Network and a Terminating Network could separate the Service Network and the Called Party. Note that the translation database provides the capability to translate the ETNS number into a routeing number or signalling address. The translation database capability can be provided in a number of ways, e.g., Intelligent Network or internal switch translations. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)11 CallingPartyCalledPartyServiceExchangeServingExchangeETNStranslationdatabaseService Network and Service ProducerServing NetworkCallingPartyCalledPartyServingExchangeETNStranslationdatabaseService NetworkServing NetworkService ProducerServiceExchangeCallingPartyCalledPartyServingExchangeETNStranslationdatabaseServiceExchangeServing Network,Service networkand Service ProducerCallingPartyCalledPartyServingExchangeETNStranslationdatabaseServiceExchangeServing Network,Service networkService Producer NOTE: In the figure the ETNS translation database could be outside the serving network.
Figure 2: Examples of call handling 4.2 Non-call related (Management part)
Two functions are performed by the registrar. The first is the number assignment process. The second is the distribution of routeing numbers bound to ETNS numbers to SgNs. 4.2.1 ETNS number assignment The ETNS registrar database is primarily used in the interaction between the registrar and the Service Providers for number assignment. The procedures are outlined in the ETO Report [7]. 4.2.2 Obtaining Routeing numbers (Rns) ETNS Service Providers negotiate with the Service Producer and Service Network to obtain Routeing numbers, Rns. 4.2.3 Distribution of ETNS Routeing numbers (Rns) The distribution of routeing information to the SgNs occurs, for example, when: • a new En has been assigned; • coverage of an En has changed; • an En has been withdrawn; • a change of ETNS Service Network has occurred; • a change of ETNS Service Provider has occurred, that may entail new ETNS Routeing numbers. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)12 The procedure for the distribution of the ETNS Rns to the SgNs takes place through the registrar. It is assumed that the ETNS Service Provider has obtained the ETNS Rns from the ETNS service producer(s) it has agreement with, who in turn has obtained the Rn from the service network(s) it has agreement with. The service network will have obtained routeing numbers directly or indirectly from the national numbering authority. Figure 3 illustrates an example of the distribution of routeing numbers when updating the ETNS translation databases. The ETNS Service Provider informs the registrar of the ETNS numbers and its connected ETNS Routeing numbers. The registrar distributes ETNS numbers and their connected ETNS Routeing numbers to the relevant SgNs (see reference point E in figure 1): • SgN1 would need to use Rn(a); • SgN2 does not receive an Rn as in this example the customer has stated that they do not require service from this location; • SgNs 3 and 4 use a common number Rn(b). Service ProviderSgN1SgN2SgN3SgN4ServiceProducerRegistrarRn(a)Rn(b)Rn(b) Figure 3: Distribution of Routeing Numbers 5 Routeing The present document describes the requirements to enable the routeing of ETNS calls, i.e. the routeing method, the structure of the ETNS Routeing numbers and the addressing between networks. 5.1 Routeing methods In general double translation shall be used for the routeing of calls between the calling and called party although in some cases this could be reduced to a single translation as an implementation option.
5.1.1 Single translation Void. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)13 5.1.2 Double translation Double translation can be implemented in two ways as illustrated in figure 4: • implementation A: utilizing the speech path between the serving exchange and the service exchange and the signalling path between the service exchange and the ETNS service producer database; • implementation B: utilizing only the signalling path between the serving/service exchange and the ETNS service producer database. Each routeing decision is based upon analysing a minimum of the following addressing parameters: the dialled En, an ETNS Rn, an ETNS signalling address or the Tn.
EnTNEnUsed speech pathUsed signalling pathSATNImplementation BThe oval identifies the terminationof the signalling connectionCallingPartyCalledPartycombined serving and service exchangeETNS translation databaseETNS service producerdatabase
EnRnEnRnRnTNTNImplementation Aserving exchangeCallingPartyCalledPartyETNS translationdatabaseETNS serviceproducer databaseservice exchange Figure 4: Double translation If the ETNS translation database is not in the same network as the serving exchange then a standardized interface is required between the two entities. Implementation method B requires a standardized signalling interface between the ETNS translation database and the ETNS Service Producer database. For example a standardized translation between the Intelligent Network (IN) signalling and ISDN User Part (ISDN ISUP) v2 [6]. The combined serving/service exchange and the ETNS translation database are normally co-located within one network. The oval illustrates that the exact termination of the signalling connection within the IN-architecture is not decided. The consequence of direct interrogation between the databases is effectively to co-locate the service exchange and the serving exchange functional entities. Non-standardized interfaces or any combinations of the above methods can be used between networks by bilateral agreements. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)14 NOTE: Double Translation Implementation Method B may, where not precluded by national licensing and regulatory conditions, provide choice to the ETNS subscriber by allowing the ETNS service Producer to utilize Carrier Selection Code(s) as defined in TR 101 092 [4] within or as a prefix to the ETNS Terminating Number (ETNS Tn). This is the case when the ETNS Service Network and the network selected by the Carrier Selection Code(s) are within the same national numbering scheme. 5.2 Structure of ETNS Routeing numbers The ETNS Routeing numbers shall, as a minimum, identify the service network. The creation of an Rn series for ETNS is a national matter. ETNS Routeing numbers are assigned to service networks. These ETNS Routeing numbers are a demand on national numbering resources. The structure of ETNS Routeing numbers shall be a national matter. Change of service network means change of ETNS Rn, while change of ETNS service provider within one service network should not necessarily mean a change of Rn. 5.3 Addressing between networks Implementation A identified for double translation in clause 5.1.2 utilizes Routeing numbers to locate the ETNS service network database. The addressing can take place in two ways, determined by what the Routeing numbers identify and how they are transferred between the ETNS translation database and the ETNS service network. The two addressing methods can be described as: 1) ETNS Rn identifying the called party and the ETNS service network (Rn1); 2) ETNS Rn identifying ETNS service network only (Rn2). Implementation B identified for double translation in clause 5.1.2 utilizes Signalling Addresses to locate the ETNS service producer database. To understand the differences between the two addressing methods for double translation, we need to look at the addresses at the reference points identified in the call-related part of figure 1. Figure 5 shows 3 interfaces between a calling and called party at which the transferred addresses will be identified. These interfaces are: C) in front of the Serving exchange; B) between the serving and service exchange (this applies for implementation A) and between the signalling termination points (this applies for implementation B); F) after the service exchange. Speech connectionsSignalling connectionsInterface C, B or FCimplementation AFThe oval identifies the terminationof the signalling connection.CalledPartyCallingPartyserving exchangeservice exchangeETNS translationdatabaseETNS serviceproducer databaseimplementation BBB Figure 5: Interfaces where addresses are identified SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)15 Table 1 shows the addresses in the call setup direction, at the three mentioned interfaces for double translation utilizing addressing methods 1 and 2. For double translation the differences between addressing methods 1 and 2 are identified. Table 1: Addresses for double translation Addressing method Interface C Interface B Interface F Implementation A, Addressing method 1 En (see note) Rn1 Tn Implementation A, Addressing method 2 En (see note) Rn2 and En towards the ETNS Service Network.
Tn Implementation B, En (see note) Signalling address plus En towards the ETNS Service Producer database, and Tn from it. Tn NOTE: The international prefix is not part of the En.
One En can be translated into different Routeing numbers and signalling addresses depending upon the origin of the call. With addressing method 1 (implementation A), there is a one-to-one translation from En via Rn1 to Tn. Rn1 identifies both the called ETNS subscriber and the ETNS service network. The trigger for the first translation from En to Rn1 takes place within the SgN, and the trigger for the second translation from Rn1 to Tn takes place within the ETNS service network. Addressing method 1 is an initial solution. In addressing method 1 part of the subscriber dependant digits may be used to address the Service Producer, see clause B.1. With addressing method 2 (implementation A), the first translation of En, in the ETNS Serving Network creates Rn2, which is the address of the ETNS Service Network. The ETNS Service Network forwards the call to the ETNS Service Producer. When the ETNS Service Producer receives the En, it translates the En to the Tn. Addressing method 2 (implementation A), requires advanced signalling systems, see annex C. Extra digits may be required to be carried with the Rn2 to identify the ETNS Service Producer at the ETNS Service Network. This should remain a national matter. One ETNS Service Network can have more than one identity (Rn2), for different purposes. With addressing method 2 (implementation A), it is required that both Rn2 and En be transferred across interface B. Addressing method 2 (implementation A),should be used as soon as the capability for this is available between any Serving Network/Service Network pair. Implementation B shall be implemented with standard signalling systems, for details see annex C.
Dialled calls to Routeing numbers shall be barred. 6 Number portability within the ETNS Number portability within the ETNS means a change of ETNS Service Provider. Porting of ETNS numbers involving a change of service network will require a change of Routeing numbers. Porting of ETNS numbers not involving a change of service network may not require a change of Routeing numbers. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)16 Annex A (Informative): Routeing of calls to corporate networks (CN) A.1 Model for actors involved Figure A.1 shows a model of the actors involved in the routeing of calls to a corporate network (CN) implemented within the ETNS.
CC1
CC2
CC3
CN
CN
Calling party
Called party
Called party
SgN/ScN/TN
AN/SgN/ScN
TN
Figure A.1: Actors and reference points The model shows 3 countries (CC1, CC2 and CC3), in which the actors, represented by their function(s), are located. In CC1 we have assisted networks (ANs), serving networks (SgNs) or service networks (ScNs) and/or combinations of these. In CC2 we have SgNs, ScNs or terminating networks (TNs) and/or combinations of these. In CC3 we have only TNs. In the model the functions are divided between 3 countries, but all functions can of course be located within one country. The bold oval in the figure represents the public network in these three different countries. The two CNs in figure A.1 represent one (1) corporate network (CN), connected to the public network in 2 different countries (CC2 and CC3). Each part of the CN may utilize its own ScN. A.2 Routeing methods Three different methods for routeing of calls to CNs have been identified: - double translation; - single translation; - direct routeing. For each of these methods we have in the following clauses described the routeing, the utilized numbering/addressing formats, the necessary actions to implement number portability for each of the methods, and the consequences for the involved public actors if the individual parts of the CN are not interconnected. Figure A.2 shows the interfaces where the numbering/addressing formats are identified.
Assisted
Network
Serving
Network
alling party
Service
Network
Terminating
Network
Called party
B
C
F
Figure A.2: Interfaces Interface C is in front of the SgN, interface B is between SgN and ScN and interface F is after the ScN. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)17 A.2.1 Double translation Four examples of double translation are described below. Each example is characterized by the location of SgN and ScN, and whether the traffic is routed into the CN through 1 or 2 access points. A.2.1.1 Example 1: SgN and ScN located in different countries and 2 access points into the CN Figure A.3 shows the routeing of calls from the calling party in the public network to the CN, the location of SgN and ScN, and where in the call set up procedure the Ens (ETNS numbers), the Rns (Routeing numbers) and the Tns (Terminating numbers) are used.
TnCC1 CC2 CC3 CN CN Calling party Called party Called party ScN SgN En Rn Tn2 TN TN B F C
Figure A.3: Routeing of calls in example 1 The horizontal dashed line represents the route of the call, and the dips on the line represent SgN and ScN. Figure A.3 shows that the SgN is located in CC1, one or more ScN are located in CC2, and that both access points into the CN are used. Table A.1 shows the numbering/addressing formats of the identified parameters at the interfaces. Table A.1: Formats for example 1 One or more ScNs In front of SgN
Between SgN and ScN
After the ScN
One ScN per corporate network En: 38835+CNID+CNSN Rn: CC2+NDC+SN Tn2: NDC2+SN2 Tn3: CC3+NDC3+SN3 En: 38835+CNID+CNSN RnA: CC2+NDC(ScN1)+SN Tn2: NDC2+SN2 More ScNs per corporate network (see note) En: 38835+CNID+CNSN RnB: CC2+NDC(ScN2)+SN Tn3: CC3+NDC3+SN3 NOTE: The ScNs may be located in different countries.
When a CN is served by more ScNs, the routeing numbers address the individual ScN, as shown in table A.1. RnA and RnB address the two ScNs, serving the part of the CN that is located in CC2 and CC3 respectively.
The numbering/addressing formats shown in the table are independent of whether the individual parts of the CN are interconnected or not. Tn2 can optionally be in the international format CC2+NDC2+SN2. Service provider portability is achieved through change of Rns. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)18 A.2.1.2 Example 2: SgN and ScN located in different countries and 1 access point into the CN Figure A.4 shows the routeing of calls from the calling party in the public network to the CN, the location of SgN and ScN, and where in the call set up procedure the Ens, the Rns and the Tns are used.
Tn3 CC1 CC2 CC3 CN CN Calling party Called party Called party ScN SgN En Rn Tn2 TN TN B F C
Figure A.4: Routeing of calls in example 2 The horizontal dashed line represents the route of the call, and the pits on the line represent SgN and ScN. Figure A.4 shows that the SgN is located in CC1, ScN is located in CC2, and that only the access point in CC3 is used to reach the CN. Table A.2 shows the numbering/addressing formats of the identified parameters at the C, B and F interface. Table A.2: Formats for example 2 One or more ScNs In front of SgN
Between SgN and ScN
After the ScN
One ScN per corporate network En: 38835+CNID+CNSN Rn: CC2+NDC+SN Tn2: CC2+NDC2+SN2 Tn3: CC3+NDC3+SN3 En: 38835+CNID+CNSN RnA: CC2+NDC(ScN1)+SN Tn2: CC2+NDC2+SN2 More ScNs per corporate network (see note) En: 38835+CNID+CNSN RnB: CC2+NDC(ScN2)+SN Tn3: CC3+NDC3+SN3 NOTE: The ScNs may be located in different countries.
When a CN is served by more ScNs, the routeing numbers address the individual ScN, as shown in table A.2. RnA and RnB address the two ScNs, serving the CNs terminating numbers in CC2 and CC3 respectively. To be able to reach all called parties in the CN, the individual parts of the CN has to be interconnected as shown in figure A.4. Without this internal connection the involved public networks would have to utilize both access points into the CN. The numbering/addressing formats after the ScN will then have to be as in table A.1.
Service provider portability is achieved through change of Rns. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)19 A.2.1.3 Example 3: SgN and ScN located in 1 country and 2 access points into the CN Figure A.5 shows the routeing of calls from the calling party in the public network to the CN, the location of SgN and ScN, and where in the call set up procedure the Ens, the Rns and the Tns are used.
Tn3 CC1 CC2 CC3 CN CN Calling party Called party Called party SgN AN En Rn Tn2 ScN TN B F C
Figure A.5: Routeing of calls in example 3 The horizontal dashed line represents the route of the call, and the dips on the line represent SgN and ScN. Figure A.5 shows that SgN and ScN are both located in CC2, and that both access points into the CN are used. Table A.3 shows the numbering/addressing formats of the identified parameters at the interfaces. Table A.3: Formats for example 1 One or more ScNs In front of SgN
Between SgN and ScN
After the ScN
One ScN per corporate network En: 38835+CNID+CNSN Rn: NDC+SN Tn2: NDC2+SN2 Tn3: CC3+NDC3+SN3 En: 38835+CNID+CNSN RnA: NDC(ScN1)+SN Tn2: NDC2+SN2 More ScNs per corporate network (see note) En: 38835+CNID+CNSN RnB: NDC(ScN2)+SN Tn3: CC3+NDC3+SN3 NOTE: The ScNs may be located in different countries.
When a CN is served by more ScNs, the routeing numbers address the individual ScN, as shown in table A.3. RnA and RnB address the two ScNs, serving the part of the CN that is located in CC2 and CC3 respectively. The numbering/addressing formats shown in the table are independent of whether the individual parts of the CN are interconnected or not. Tn2 can optionally be in the international format CC2+NDC2+SN2. Service provider portability is achieved through change of Rns. SIST EN 301 160 V1.2.1:2005

ETSI ETSI EN 301 160 V1.2.1 (2002-01)20 A.2.1.4 Example 4: SgN and ScN located in 1 country and 1 access point into the CN Figure A.6 shows the routeing of calls from the calling party in the public network to the CN, the location of SgN and ScN, and where in the call set up procedure the Ens (ETNS numbers), the Rns (Routeing numbers) and the Tns (Terminating numbers) are used.
Tn3 CC1 CC2 CC3 CN CN Calling party Called party Called party SgN AN En Rn Tn2 ScN TN B F C
Figure A.6: Routeing of calls in example 4 The horizontal dashed line represents the route of the call, and the dips on the line represent SgN and ScN. Figure A.6 shows that the SgN and ScN are both located in CC2, and that only the access point in CC3 is used into the CN. Table A.4 shows the numbering/addressing formats of the identified parameters at the interfaces. Table A.4: Formats for example 4 One or more ScNs In front of SgN
Between SgN and ScN
After the ScN
One ScN per corporate network En: 38835+CNID+CNSN Rn: NDC+SN Tn2: CC2+NDC2+SN2 Tn3: CC3+NDC3+SN3 En: 38835+CNID+CNSN RnA: NDC(ScN1)+SN Tn2: CC2+NDC2+SN2 More ScNs per corporate network (see note) En: 38835+CNID+CNSN RnB: NDC(ScN2)+SN Tn3: CC3+NDC3+SN3 NOTE: The ScNs may be located in different countries.
When a CN is served by more ScNs, the routeing numbers address the individual ScN, as shown in table A.4. RnA and RnB address the two ScNs, serving the CNs terminating numbers in CC2 and CC3 respectively. To be able to reach all called parties in the CN, the individual parts of the CN has to be interconnected as shown in figure A.6. Without this internal connection the involved public networks would have to utilize both access points into the CN, and the routeing and the numbering/addressing formats after the ScN will then have to be as in table A.3.
Service provider portability is ac
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