ETSI TS 123 066 V16.0.0 (2020-07)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Support of Mobile Number Portability (MNP); Technical realization; Stage 2 (3GPP TS 23.066 version 16.0.0 Release 16)

RTS/TSGC-0423066vg00

General Information

• Status: Not Published
• Technical Committee: 3GPP CT 4 - MAP/CAMEL/GTP/BCH/SS/TrFO/IMS/GUP/WLAN (formely CN4)
• Current Stage: 12 - Completion
• Completion Date: 20-Jul-2020

Standards Content (Sample)

TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
Support of Mobile Number Portability (MNP);
Technical realization;
Stage 2
(3GPP TS 23.066 version 16.0.0 Release 16)

R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS

3GPP TS 23.066 version 16.0.0 Release 16 1 ETSI TS 123 066 V16.0.0 (2020-07)

Reference
RTS/TSGC-0423066vg00
Keywords
GSM,UMTS
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3GPP TS 23.066 version 16.0.0 Release 16 2 ETSI TS 123 066 V16.0.0 (2020-07)
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Legal Notice
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The present document may refer to technical specifications or reports using their 3GPP identities. These shall be
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ETSI
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Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 General . 9
4.1 Overview . 9
4.2 Compatibility . 10
4.3 Common Functionality of the MNP-SRF . 11
5 Common Architecture for call setup . 14
6 Functional requirements of network entities . 16
6.1 Procedure MNP_MT_GMSC_Set_MNP_Parameters . 16
6.2 Procedure MNP_MT_GMSC_Check_MNP_Indicators . 17
6.3 Procedure MNP_SRF_Check_MNP_Indicator . 18
Annex A (normative): IN Call-Related Technical Realisation . 19
A.1 Architecture . 19
A.1.1 Network Options . 19
A.1.2 No NP Query required – Number is not subject for portability . 19
A.1.3 NP Query in Number Range Holder Network . 20
A.1.3.1 TQoD – Number is not ported . 20
A.1.3.2 TQoD – Number is ported . 21
A.1.3.3 QoHR – Number is ported . 22
A.1.4 NP Query in Originating Network . 23
A.1.4.1 OQoD – Number is not ported . 23
A.1.4.2 OQoD – Number is ported . 24
A.1.4.3 IN-Query for CAMEL pre-paid service . 25
A.2 Information flows . 27
A.3 Functional requirements of network entities . 33
A.3.1 Functional requirement of GMSC . 33
A.3.1.1 Procedure MOBILE_NUMBER_PORTABILITY_IN_QoHR . 33
A.3.1.2 Procedure MOBILE_NUMBER_PORTABILITY_IN_TQoD . 35
A.3.2 Functional requirement of MSC . 36
A.3.2.1 Procedure MOBILE_NUMBER_PORTABILITY_IN_OQoD . 36
A.3.3 Functional requirement of NPDB . 38
A.3.3.1 Process IN_QUERY_NPDB . 38
A.4 Contents of messages . 39
A.4.1 Messages on the ISUP interface . 39
A.4.1.1 IAM for ETSI ISUP interface . 39
A.4.1.2 IAM for ANSI ISUP interface . 39
A.4.2 Messages on the MSC - NPDB interface . 39
A.4.2.1 INITIAL DP. 39
A.4.2.2 INITIAL DP negative response . 40
A.4.2.3 CONNECT . 40
A.4.2.4 CONTINUE . 40
A.4.2.5 RELEASE CALL . 40
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A.4.2.6 ProvideInstruction:Start . 40
A.4.2.7 ConnectionControl:Connect . 41
Annex B (normative): Handling of Non-Call Related Signalling . 42
B.1 Handling of Non-call Related Signalling . 42
B.1.1 Routeing Conventions . 42
B.1.2 Network Architecture . 42
B.2 Signalling Scenarios . 44
B.2.1 Non-call Related Signalling Message for a Non-ported Number – Indirect Routeing . 44
B.2.2 Non-call Related Signalling Message for a Ported or Non-ported Number – Direct Routeing . 45
B.2.3 Non-call Related Signalling Message for a Ported Number - Indirect Routeing . 46
B.3 Functional Requirements of Network Entities . 46
B.3.1 Procedure MNP_SRF_Non_Call_Related . 46
B.4 Signalling Scenarios (informative) . 49
B.4.1 Delivery of SMS to a Non-ported Number – Direct Routeing – MNP-SRF acts as SCCP Relay . 49
B.4.2 Delivery of SMS to a Non-ported Number - Direct Routeing – MNP-SRF acts as Higher-level Relay . 50
B.4.3 Delivery of SMS to a Ported Number – Indirect Routeing . 51
B.4.4 Delivery of SMS to a Ported Number – Direct Routeing . 51
B.4.5 International SOR for a Non-ported Number . 53
B.4.6 SOR for a Ported Number – Indirect Routeing . 54
B.4.7 Any Time Interrogation for a Ported Number – Indirect Routeing . 55
B.4.8 Any Time Interrogation for a Ported Number – Direct Routeing . 56
B.4.9 CCBS where the Busy Subscriber is a Ported Subscriber - Direct Routeing . 57
B.4.10 Calling Name Presentation Flows – MNP-SRF acts as SCCP Relay . 58
Annex C (normative): MNP Signalling Relay Function - Call Related Signalling . 59
C.1 Handling of Call Related Signalling. 59
C.2 Functional Requirements of Network Entities . 60
C.2.1 Procedure MNP_SRF_MATF_Call_Related . 60
C.2.2 Process SRI_NPLR . 60
C.2.3 Procedure MNP_SRF_MATF_Info_Request . 61
C.2.4 Process ATI_NPLR . 61
C.3 Call Scenarios . 66
C.3.1 Call to a Non-Ported Number or Number Ported into the Network . 67
C.3.2 Call to a Ported Number – Originating Network = Subscription Network – Direct Routeing . 68
C.3.3 Mobile Originated Call to a Ported or not known to be Ported Number – Originating Network
≠Subscription Network– Direct Routeing . 69
C.3.4 Call to a Ported Number – Indirect Routeing . 70
C.3.5 Call to a Ported Number – Indirect Routeing with Reference to Subscription Network . 71
C.3.6 MNP Info Query - Direct Routeing . 72
C.3.7 MNP Info Query - Indirect Routeing . 73
C.4 Information Flows . 74
C.5 Contents of the messages . 79
C.5.1 Send Routeing Info . 80
C.5.2 Send Routeing Info ack . 80
C.6 Handling of MAP to ISUP mapping (informative) . 80
C.6.1 ETSI Mapping direction: ISUP to MAP . 80
C.6.2 ETSI Mapping direction: MAP to ISUP . 80
C.6.3 ANSI Mapping direction: ISUP to MAP . 81
C.6.4 ANSI Mapping direction: MAP to ISUP . 81
Annex D: Void . 83
Annex E (informative): Change history . 84
History . 85
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Foreword
rd
This Technical Specification (TS) has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
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1 Scope
The present document describes several alternatives for the realisation of Mobile Number Portability.
The present document includes information applicable to network operators, service providers, switch and database
manufacturers and national regulators.
It is left to operator and implementation decisions which option, or combination of options, is used, taking into account
the regulatory and architectural constraints that may prevail. The possible implications of these options on internal node
functions and on signalling performance are not covered in the present document.
Normative Annex A of the present document describes the technical realisation of the handling of calls to ported UMTS
or GSM mobile subscribers using IN technology.
Normative Annex C of the present document describes the technical realisation of the handling of calls to ported UMTS
or GSM mobile subscribers using Signalling Relay technology.
Normative Annex A and Normative Annex C describe alternative solutions. The network operator may choose the
solution to be used in his network.
Normative Annex B of the present document describes the technical realisation of the handling of non-call related
SCCP signalling for ported UMTS or GSM mobile subscribers using Signalling Relay technology.
The present document does not specify the porting process.
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, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TS 21.905: "3G Vocabulary".
[2] 3GPP TS 22.066: "Support of Mobile Number Portability (MNP); Service description. Stage 1".
[3] 3GPP TS 23.018: "Basic call handling; Technical realisation".
[4] ETSI ETS 300 009 (1991): "Integrated Services Digital Network (ISDN); CCITT Signalling
System No. 7 – Signalling Connection Control Part (SCCP) [connectionless services] to support
international interconnection".
[5] ETSI ETS 300 374-1: "Intelligent Network (IN); Intelligent Network Capability Set 1 (CS1); Core
Intelligent Network Application Protocol (INAP); Part 1: protocol specification".
[6] ITU-T Recommendation Q.769.1; ISDN User Part (ISUP); Enhancements for the support of
Number Portability".
[7] ETSI EN 300 356-2 V4.1: "Integrated Services Digital Network (ISDN); Signalling System No.7;
ISDN User Part (ISUP) version 4 for the international interface; Part 2: ISDN supplementary
services [ITU-T Recommendation Q.730 modified]".
[8} CTIA report on Wireless Number Portability, Version 2.0.0.
[9] ANSI T1.660 – 1998, American National Standards for Telecommunications – Signaling System
Number 7 – NumberPortability Call Completion to a Portable Number.
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[10] ANSI T1.111-1996, American National Standards for Telecommunication – Signalling System
No. 7 (SS7) Message Transfer Part (MTP).
[11] ANSI T1.112-1996, American National Standards for Telecommunication – Signalling System
No. 7 (SS7) Signalling Connection Control Part (SCCP).
Note: Translation Types 10 and 14 will be published in the next revision of ANSI T1.112.
[12] American National Standard for Telecommunications – Signalling System Number 7 (SS7) -
ISDN User Part (ISUP) - ANSI T1.113-1995.
[13] American National Standard for Telecommunications - Signalling System Number 7 (SS7) –
Transaction Capabilities Application Part (TCAP) - ANSI T1.114-1996.
[14] ETSI EN 302 097 V1.2: "Integrated Services Digital Network (ISDN); Signalling System No.7;
ISDN User Part (ISUP); Enhancements for support of Number Portability (NP)".
[15] TI - Technical Requirements No. 3, April 1999, Number Portability Database and Global Title
Translation.
[16] 3GPP TS 23.096: "Mobile Name Identification Supplementary Service – Stage 2".
[17] North American Numbering Council (NANC) Functional Requirement Specification, Number
Portability Administration Center- Service Management System (NPAC-SMS), Version 1.0, May
25, 1995; Version 2.0, June 2, 1997.
[18] 3GPP TS 23.078: "Customised Applications for Mobile network Enhanced Logic (CAMEL) Phase
4 – Stage 2".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply.
donor network: subscription network from which a number is ported in the porting process. This may or may not be
the number range holder network
interrogating network entity: entity that submits a non-call related signalling message to interrogate the HLR
interrogating network: network in which the interrogating network entity resides
mobile number portability: ability for a mobile subscriber to change mobile network subscription within the same
country whilst retaining his/her original MSISDN(s). Additional regulatory constraints apply in North America.
mobile number portability information: an information set relevant to Mobile Number Portability for a mobile
subscriber. It may contain one or more of Routeing Number, generic IMSI MSISDN,and Number Portability Status.
network operator: GSM PLMN operator
non-call related signalling message: all signalling messages where the MSISDN is used to route the message on SCCP
level except MAP SRI without OR parameter set (i.e. SRI_SMS, SRI for SOR, Send_IMSI, CCBS_Request etc)
North American GSM Number portability: the ability for a subscriber to change subscription between North
American GSM networks and other subscription networks within a regulated geographical area within North America.
number portability database: operational database (used in real time at call set-up) which provides portability
information
number portability location register: internal MAP application terminating function (MATF) in the MNP-SRF
network entity with an (unspecified) interface with a NPDB
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number portability status: information indicating the status of number portability for a mobile subscriber. It may be
one of: own number ported out, own number not ported out, foreign number ported in, foreign number ported to a
foreign network, foreign number not known to be ported
number range holder network: network to which the number range containing the ported number has been allocated
originating network: network where the calling party is located
portability domain: set of GSM PLMNs in a country between which MSISDNs may be ported or a set of North
American GSM Mobile networks and other subscription networks within a regulated geographical area within North
America
portability network: a PLMN or ,in North America, a PSTN or an ISDN network
portable number: E.164 number that can be ported between networks in one nation
ported number: portable number that has undergone the porting process
ported subscriber: subscriber of a ported number
porting process: description of the transfer of a number between network operators
recipient network: network that receives the number in the porting process. This network becomes the subscription
network when the porting process is complete
routeing number: routeing number is the data stored against the ported number or the non-ported number in the
Number Portability Database. The routeing number points to Subscription Network or Recipient Network
service key: service Key can identify to the entity holding the Number Portability Database that the service logic for
Mobile Number Portability should apply. The Service Key value for Mobile Number Portability is administered in the
MSC, and is passed transparently to the entity holding the Number Portability Database
service provider: entity that offers service subscriptions to individual subscribers and contracts with a network operator
to implement services for a specific MSISDN. A service provider may contract with more than one network operator
service provider portability: transfer of numbers between two unique Service Providers
subscription network: network with which the customer's Service Provider has a contract to implement the customer's
services for a specific MSISDN
NOTE: The term "recipient network" is used during the porting process. The recipient network becomes the
"subscription network" after the completion of the porting process.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CCBS Call Completion on Busy Subscriber
CCF Call Completion Function
CdPA Called Party Address
CgPA Calling Party Address
CNAP Calling Name Presentation
CNDB Calling Name Database
CRMNP Call Related Mobile Number Portability
FCI Forward Call Indicator
GAP Generic Address Parameter
GMSC Gateway MSC
GMSCB The GMSC in HPLMNB
GTT Global Title Translation
HLR Home Location Register
HPLMNB The subscription network of the B subscriber
IAM Initial Address Message
IDP Initial Detection Point
IE Information Element
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INE Interrogating Network Entity
IF Information Flow
IPLMN Interrogating PLMN
MATF MAP application Terminating Function
MNP Mobile Number Portability
MNP-SRF Signalling Relay Function for support of MNP
MSA Mobile Station of the A subscriber
MSB Mobile Station of the B subscriber
MSC Mobile-services Switching Centre
MSISDN Mobile Station International ISDN Number
MSRN Mobile Station Roaming Number
NANP North American Numbering Plan
NAGNP North American GSM Number Portability
NPDB Number Portability Database
NPLMN The number range holder network of the B subscriber
NPLR Number Portability Location Register
OQoD Originating call Query on Digit Analysis
PLMN Public Land Mobile Network
QoHR Query on HLR Release
RN Routeing Number
SMS Short Message Service
SOR Support of Optimal Routeing
SRI Send Routeing Information
STP Signalling Transfer Point
TQoD Terminating call Query on Digit Analysis
TT Translation Type
VMSC The Visited MSC
VMSCB The VMSC of the B subscriber
Further GSM related abbreviations are given in 3GPP TS 21.905: "3G Vocabulary".
4 General
4.1 Overview
Mobile Number Portability (MNP) is the ability for a UMTS or GSM mobile subscriber to change the subscription
network within a portability domain whilst retaining her original MSISDN or MSISDNs.
North American GSM Number Portability (NAGNP) is the ability for a subscriber to change subscription between
North American GSM networks and other subscription networks within a regulated geographical area within North
America.
As part of the porting process administrative actions have to be performed by the network operators of the number
range holder network, donor network, recipient network and, as an option, by operators of other national UMTS or
GSM networks as follows:
a) if the number range holder network is identical with the donor network:
add an entry in the HLR;
Recipient network:
add an entry in the Number Portability Database.
add an entry in the Number Portability Database;
Donor network:
delete the entry related to the ported MSISDNs in the HLR.
Other networks in the portability add an entry in the Number Portability Database (if direct routeing is
domain: used).
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b) if the number range holder network is identical with the recipient network:
Recipient network: add an entry in the HLR;
delete any entry related to the ported MSISDN in the Number
Portability Database.
Donor network: delete any entry related to the ported MSISDN in the Number
Portability Database;
delete the entry related to the ported MSISDNs in the HLR.
Other networks in the portability delete any entry related to the ported MSISDN in the Number
domain: Portability Database.
c) if the number range holder network is different from both the recipient and the donor network:
Recipient network: add an entry in the HLR;
add an entry in the Number Portability Database.
Number range holder network: update the Number Portability Database
Donor network: delete (or update) the entry in the Number Portability Database;
delete the entry related to the ported MSISDNs in the HLR.
Other networks in the portability update the Number Portability Database (if an entry for the ported
domain: MSISDN exists).
Note that the order of sequence for the administrative actions to be performed both within a network and by different
network operators is significant with respect to prevention of disruption in service to the mobile subscriber and
prevention of looping calls between networks during the porting process.
Termination of a subscription for a ported number results in the deletion of any entry in an HLR and NPDB of that
number.
If a call fails because databases are not correctly synchronised, the network entity that detects the inconsistency will
raise an MNP specific alarm to the operation and maintenance subsystem.
The present document does not specify the porting process. It specifies the functionality needed to set-up calls to both
ported and non ported subscribers including the functionality needed to query an NPDB for MNP information (in order
to be able to charge correctly for CAMEL pre-paid calls and SMS) (Normative Annex A and Normative Annex C), and
the functionality needed to relay non-call related signalling messages to the HLR in the subscription network
(Normative Annex B) .
4.2 Compatibility
The IAM sent to the subscription network may contain additional routeing information. Within a portability domain the
method how to convey the Routeing Number in the IAM between two portability networks shall be agreed upon by the
two network operators involved (for an ITU-T ISUP solution see [6] and for an ANSI ISUP solution see [8] and [9]).
In general, IN-based and MNP-SRF (call-related) solutions are compatible and may coexist in the same portability
domain. The only restriction refers to the case where the number range holder network relays call-related MAP
messages (i.e. SRI for national calls) to the subscription network. If this solution is selected by at least one network
operator within a portability domain, all the portability networks and transit networks affected must fulfil the following
requirements:
1. The SCCP interfaces between networks in a portability domain must be agreed. This refers to the SCCP
addressing mechanism being used (e.g. number lengths, natures of address and translation types for call-related
MAP messages).
For messages that do not cross network boundaries the SCCP addressing mechanism is a choice of the network
operator.
2. The subscription network must be able to generate the SRI ack to allow the onward routeing of the call from the
number range holder network to the subscription network.
In the rest of the possible architectures for MNP, no interworking problems have been identified. In these cases,
network architectures used within one portability network (e.g. IN, MNP-SRF) are regarded as operator dependent.
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In order to avoid loops and incompatibility situations, all the networks within a portability domain shall use the same
routeing convention either direct routeing, indirect routeing or indirect routeing with reference to the Subscription
network. As an alternative, indirect routeing can interwork successfully with direct routeing if the routeing number is
transferred in the IAM or if dedicated traffic connections are used.
4.3 Common Functionality of the MNP-SRF
In a PLMN that supports mobile number portability, SCCP messages sent to an HLR may be relayed by an MNP-SRF.
Depending on the implemented solution (IN-based or MNP-SRF-based), on the type of message (call-related, non-call-
related or MNP information request) and on the porting status of the called subscriber, the MNP-SRF may modify the
SCCP called party address and route the message to a different HLR or to the subscription network, or terminate the
dialogue and response to the INE.
Figure 1 shows the general steering functionality for SCCP message routeing. It shows the SCCP routeing principle for
mobile number portability within a network.
Note that call related messages in the IN-based solution are not routed to the MNP-SRF. Therefore Normative Annex A
of the present document does not mention the MNP-SRF.
However, the usage of the IN-based solution for the call-related messages should allow operators to have the routeing of
the non call-related messages determined in the same database. See [7] for the description of the access of the MNP-
SRF (node with relay capability) to the NPDB (external database).
In order to guard against the possibility that the porting data for an MSISDN is inconsistent between PLMNs in a
porting domain, the SCCP hop counter may be used to prevent indefinite looping of messages between PLMNs. The
MNP-SRF would then decrement the SCCP hop counter for every message that is relayed. It should be noted that the
use of the SCCP hop counter requires the use of non segmented SCCP XUDT messages as defined in ITU-T 1996
SCCP recommendations or in the ANSI T1.112-1996 SCCP recommendations for North America, reference [11].
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Process SCCP_Steering_Function 1(1)
general Steering Function
for SCCP routeing
Idle
SCCP
message
OPTION
IN-based MNP-SRF-based
call related
no
yes
SCCP SCCP SCCP
to HLR to MNP-SRF to MNP-SRF
message message message
Idle Idle Idle
Figure 1: Steering Function for SCCP Message routeing
Figure 2 shows the process MNP_SRF in the MNP-SRF. The procedures MNP_SRF_MATF_Call_Related,
MNP_SRF_Non_Call_Related and MNP_SRF_MATF_Info_Request are described in Normative Annex C and
Normative Annex B of the present document. Note that in networks which support the IN-based solution for call related
signalling, a distinction on SCCP level for call related and non-call related messages is needed and that the MNP-SRF
does not require to include MATF's since call related messages and MNP information request messages are not
terminated at the MNP-SRF.
The test "MNP info-request" is a test on the SCCP Translation Type if a dedicated Translation Type value for MNP
information request messages is used in the network. The handling of SCCP messages in the MNP-SRF in networks
which do not make use of a dedicated Translation Type value for MNP information request messages is for further
study.
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The test "call-related" is a test on the SCCP Translation Type if a dedicated Translation Type value for call related
messages is used in the network. The handling of SCCP messages in the MNP-SRF in networks which do not make use
of a dedicated Translation Type value for call related messages is for further study.

Process MNP_SRF 1(1)
Process in the MNP_SRF
to relay SCCP messages
IDLE
SCCP
message
MNP info request
yes
no
see Annex C
MNP_SRF_MATF
_Info_Request
IDLE
call-related
no
yes
MNP_SRF_MATF
see Normative Annex C
_Call_Related
terminate?
yes
no
see Annex B
MNP_SRF_Non_
IDLE
Call_Related
terminate?
yes
no
SCCP
message
IDLE
SCCP
IDLE
message
IDLE
Figure 2: Process MNP_SRF
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5 Common Architecture for call setup
Figure 3 shows the general architecture of a portability domain for routeing of calls. The more detailed architecture
within the networks depends on the chosen solution (IN-based or MNP/SRF-based) and options and is described in
Normative Annex A and Normative Annex C of the present document.
The architecture for non-call related signalling is described in Normative Annex B of the present document.
SRI (4)
Number range Subscription
holder network network
SRI ack (5)
IAM(1) IAM (8)
IAM (6)
IAM (3)
IAM (2) IAM (7)
Other
national
network
Portability domain
Figure 3: General architecture of a portability domain for routeing of calls
The following routeing conventions are identified:
1. Direct Routeing of calls is a PLMN option that allows to route calls directly from the PLMN supporting this
option to the ported subscriber's subscription network.
2. Indirect Routeing of calls is a PLMN option which allows to route calls from the PLMN supporting this option
via the number range holder network to the ported subscriber's subscription network.
3. Indirect Routeing of calls with reference to the subscription network is a PLMN option for PLMN operators
having chosen the MNP-SRF solution for call related signalling described in Normative Annex C. If all PLMNs
within a portability domain support this option, calls are routed from the originating network to the number
range holder network. The number range holder network obtains onward routeing information from the
subscription network and routes the call onward to the ported subscriber's subscription network.
The following action in the different networks can be identified:
1. If the call is originated outside the portability domain, the IAM (1) is received by the number range holder
network.
2a. If the call is originated in another national network and the other national network does not support originating
call query (i.e. Indirect Routeing of calls is applicable), the IAM (2) is received by the number range holder
network.
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2b. If the call is originated in another national network and the other national network supports originating call query
(i.e. Direct Routeing of calls is applicable), the IAM (7) containing the routeing number is sent to the
subscription network. If the routeing number is not used in the IAM sent from the national originating network to
the subscription network, all transit networks involved are required to look up an NPDB in order to retrieve
routeing information to route the call to the subscription network without looping.
3a. If the call is originated in the subscription network and the subscription network does not support originating call
query (i.e. Indirect Routeing of calls is applicable), the IAM (3) is received by the number range holder network.
3b. If the call is originated in the subscription network and the subscription network supports originating call query
(i.e. Direct Routeing of calls is applicable), it sends an IAM (8) containing the MSRN to the visited network of
the called subscriber.
3c. If the subscription network
...