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TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
Explicit Communication Transfer (ECT)
using IP Multimedia (IM) Core Network (CN) subsystem;
Protocol specification
(3GPP TS 24.629 version 15.0.0 Release 15)
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3GPP TS 24.629 version 15.0.0 Release 15 1 ETSI TS 124 629 V15.0.0 (2018-07)
Reference
RTS/TSGC-0124629vf00
Keywords
GSM,LTE,UMTS
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GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 2 ETSI TS 124 629 V15.0.0 (2018-07)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 3 ETSI TS 124 629 V15.0.0 (2018-07)
Contents
Intellectual Property Rights . 2
Foreword . 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 . 7
4 Explicit Communication Transfer (ECT) . 8
4.1 Introduction . 8
4.2 Description . 8
4.2.1 General description . 8
4.3 Operational requirements . 8
4.3.1 Provision/withdrawal . 8
4.3.2 Requirements on the transferor network side . 8
4.3.3 Requirements on the transferee network side . 8
4.3.4 Requirements on the transfer target network side . 8
4.4 Coding requirements . 9
4.5 Signalling requirements . 9
4.5.1 Activation/deactivation . 9
4.5.1A Registration/erasure . 9
4.5.1B Interrogation . 9
4.5.2 Invocation and operation . 9
4.5.2.1 Actions at the transferor UE . 9
4.5.2.2 Void. 10
4.5.2.3 Void. 10
4.5.2.4 Actions at the transferor AS . 10
4.5.2.4.1 Invocation of ECT service . 10
4.5.2.4.1.1 Prerequisite for invocation of the ECT service . 10
4.5.2.4.1.2 Determine whether the ECT applies . 11
4.5.2.4.1.2.1 REFER request received on a separate dialog . 11
4.5.2.4.1.2.2 REFER request received in the to be transferred dialog . 11
4.5.2.4.1.2.2A Procedures for call transfer with 3PCC . 11
4.5.2.4.1.2.3 Actions of ECT when invoked with a transfer request . 12
4.5.2.4.2 Subsequent procedures . 12
4.5.2.4.2.1 Actions of ECT when invoked again by the transferred communication. 12
4.5.2.5 Actions at the transferee UE. 13
4.5.2.5.1 Actions at the transferee UE (without 3PCC) . 13
4.5.2.5.2 Actions at the transferee UE (with 3PCC) . 13
4.5.2.6 Void. 13
4.5.2.7 Actions at the transferee AS . 13
4.5.2.7.0 Prerequisite for invocation of the ECT service . 13
4.5.2.7.1 Determine whether ECT applies . 13
4.5.2.7.2 Actions of the ECT AS when invoked with a transfer request . 13
4.5.2.7.3 Actions of the ECT AS when invoked again by the transferred communication . 14
4.5.2.8 Void. 14
4.5.2.9 Void. 14
4.5.2.10 Void. 14
4.5.2.11 Void. 14
4.5.2.12 Void. 14
4.5.2.13 Void. 14
4.5.2.14 Void. 14
4.5.2.15 Actions at the transfer target's AS . 14
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 4 ETSI TS 124 629 V15.0.0 (2018-07)
4.5.2.16 Void. 14
4.5.2.17 Actions at the transfer target's UE . 14
4.6 Interaction with other services . 15
4.6.1 Communication HOLD (HOLD) . 15
4.6.2 Terminating Identification Presentation (TIP) . 15
4.6.3 Terminating Identification Restriction (TIR) . 15
4.6.4 Originating Identification Presentation (OIP) . 15
4.6.5 Originating Identification Restriction (OIR) . 15
4.6.6 CONFerence Calling (CONF) . 15
4.6.7 Communication DIVersion Services (CDIV) . 15
4.6.8 Malicious Communication IDentification (MCID) . 15
4.6.9 Anonymous Communication Rejection and Communication Barring (ACR/CB) . 15
4.6.10 Explicit Communication Transfer (ECT) . 16
4.6.10.1 Determine whether a previously transferred communication is transferred again . 16
4.6.10.2 Handling of transfer requests . 16
4.6.10.3 Actions when this ECT instance is invoked again by the transferred communication . 16
4.6.11 Enhanced Calling Name (eCNAM) . 16
4.7 Interworking with other networks . 16
4.7.1 Void . 16
4.7.2 Void . 16
4.7.3 Void . 16
4.8 Parameter values (timers) . 16
4.9 Service configuration . 17
Annex A (informative): Signalling flows . 18
A.1 Blind transfer . 18
A.2 Consultative transfer. 21
A.3 Blind call transfer with third party call control . 22
A.4 Consultative call transfer with third party call control . 23
Annex B (informative): Example of filter criteria . 24
B.1 Example of filter criteria for ECT . 24
Annex C (informative): Example charging model . 25
C.1 Example of B REFER's A to C . 25
C.2 Example of A REFER's B to C . 26
Annex D (informative): Void . 27
Annex E (informative): Change history . 28
History . 29
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 5 ETSI TS 124 629 V15.0.0 (2018-07)
Foreword
This Technical Specification (TS) was been produced by ETSI Technical Committee Telecommunications and Internet
converged Services and Protocols for Advanced Networking (TISPAN) and originally published as
ETSI TS 183 029 [11]. It was transferred to the 3rd Generation Partnership Project (3GPP) in January 2008.
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.
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 6 ETSI TS 124 629 V15.0.0 (2018-07)
1 Scope
The present document specifies the stage three (protocol description) of the Explicit Communication transfer (ECT)
supplementary service, based on stage one and two of the ISDN ECT supplementary service. It provides the protocol
details in the IP Multimedia (IM) Core Network (CN) subsystem based on the Session Initiation Protocol (SIP) and the
Session Description Protocol (SDP).
The present document is applicable to User Equipment (UE) and Application Servers (AS) which are intended to
support the ECT supplementary service.
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 24.229: "Internet Protocol (IP) multimedia call control protocol based on Session
Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3".
[2] IETF RFC 3515: "The Session Initiation Protocol (SIP) Refer Method".
[3] IETF RFC 3892: "The Session Initiation Protocol (SIP) Referred-By Mechanism".
[4] IETF RFC 3891: "The Session Initiation Protocol (SIP) "Replaces" Header".
[5] Void.
[6] IETF RFC 3261: "SIP: Session Initiation Protocol".
[7] 3GPP TS 29.228: "IP Multimedia (IM) Subsystem Cx and Dx Interfaces; Signalling flows and
message contents".
[7A] 3GPP TS 29.229: "Cx and Dx interfaces based on the Diameter protocol; Protocol details".
[8] 3GPP TS 24.610: "Communication HOLD (HOLD) using IP Multimedia (IM) Core Network
(CN) subsystem; Protocol specification".
[9] 3GPP TS 24.605: "Conference (CONF) using IP Multimedia (IM) Core Network (CN) subsystem;
Protocol specification".
[10] 3GPP TS 24.628: "Common Basic Communication procedures using IP Multimedia (IM) Core
Network (CN) subsystem; Protocol specification".
[11] ETSI TS 183 029 V2.5.0: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); PSTN/ISDN simulation services: Explicit Communication
Transfer (ECT); Protocol specification".
[12] 3GPP TS 24.315: "IP Multimedia Subsystem (IMS) Operator Determined Barring (ODB);
Stage 3".
[13] IETF RFC 7090 (April 2014): "Public Safety Answering Point (PSAP) Callback".
[14] IETF RFC 6665: "SIP-Specific Event Notification".
[15] IETF RFC 4538: "Request Authorization through Dialog Identification in the Session Initiation
Protocol (SIP)".
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 7 ETSI TS 124 629 V15.0.0 (2018-07)
[16] IETF RFC 7647 (September 2015): "Clarifications for the Use of REFER with RFC6665".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
ECT session identifier URI: PSI created and inserted by an ECT AS that resolves to the AS itself
NOTE 1: If this URI contains correlation information it has to be constructed in such a way that it does not reveal
identity information about any party involved in the transfer.
transferee: party being transferred to the transfer target
transferor: party initiating the transfer
transfer target: party that the existing communication is transferred to
NOTE 2: After transfer the transferee and the transfer target are in communication with each other.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACR Anonymous Communication Rejection
AS SIP Application Server
CDIV Communication DIVersion
CONF CONFerence
CSCF Call Session Control Function
ECT Explicit Communication Transfer
GRUU Globally Routable User agent URI
HOLD communication HOLD
IETF Internet Engineering Task Force
IFC Initial Filter Criteria
ISDN Integrated Services Digital Network
MCID Malicious Call IDentification
MGCF Media Gateway Control Function
OCB Outgoing Communication Barring
ODB Operator Determined Barring
OIP Originating Identification Presentation
OIR Originating Identification presentation Restriction
PSAP Public Safety Answering Point
PSTN Public Switch Telephone Network
S-CSCF Serving-CSCF
SIP Session Initiation Protocol
TIP Terminating Identification Presentation
TIR Terminating Identification presentation Restriction
UE User Equipment
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 8 ETSI TS 124 629 V15.0.0 (2018-07)
4 Explicit Communication Transfer (ECT)
4.1 Introduction
The service provides a party involved in a communication to transfer that communication to a third party.
Procedures for the ECT AS regarding operator determined barring (ODB) are defined in 3GPP TS 24.315 [12].
4.2 Description
4.2.1 General description
The explicit communication transfer (ECT) service provides a party involved in a communication to transfer that
communication to a third party.
There are three actors active in a transfer, they are acting in the following roles:
transferor: the party that initiates the transfer of the active communication that it has with the transferee;
transferee: the party which stays in the communication which is transferred;
transfer target: the party which the communication is transferred to and which replaces the transferor in the
communication.
There are two initial situations in which transfer shall be possible:
- the transferor has no ongoing consultation communication with the transfer target (blind/assured transfer), then
either:
a) the transferor wants to perform the transfer without any further action on the transfer operation (blind
transfer); or
b) the transferor wants to have a feedback on the transfer operation progress with the possibility to retrieve the
communication with the transferee (assured transfer); or
- the transferor has a consultation communication with the transfer target (consultative transfer).
The transferor AS takes care that it remains in the signalling path even after the communication is transferred, this
allows:
- classical charging models;
- anonymization of the transfer target.
4.3 Operational requirements
4.3.1 Provision/withdrawal
The ECT service may be provided after prior arrangement with the service provider or be generally available.
4.3.2 Requirements on the transferor network side
No specific requirements are needed in the network.
4.3.3 Requirements on the transferee network side
No specific requirements are needed in the network.
4.3.4 Requirements on the transfer target network side
No specific requirements are needed in the network.
ETSI
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3GPP TS 24.629 version 15.0.0 Release 15 9 ETSI TS 124 629 V15.0.0 (2018-07)
4.4 Coding requirements
A user agent that wishes to use the ECT service (to act as a transferor):
- Shall support the REFER method as a client as specified in RFC 3515 [2] as updated by IETF RFC 6665 [14]
and IETF RFC 7647 [16].
- Shall support the Referred-By header field as specified in RFC 3892 [3].
- Shall support the Target-Dialog header field as specified in RFC 4538 [15].
A user agent that is the transferred party in a communication transfer (acts as the transferee):
- Shall support the REFER method as a server as specified in RFC 3515 [2] and updated by RFC 6665 [14].
- Shall support the Referred-By header field as specified in RFC 3892 [3].
- Shall support Replaces header field as a client as specified in RFC 3891 [4].
- Shall support the Target-Dialog header field as specified in RFC 4538 [15].
A user agent that is the transfer target in a communication transfer:
- May support the Referred-By header field as a server as specified in RFC 3892 [3].
- May support the Replaces header field as a server as specified in RFC 3891 [4].
4.5 Signalling requirements
4.5.1 Activation/deactivation
The ECT service is activated at provisioning and deactivated at withdrawal.
4.5.1A Registration/erasure
The ECT service requires no registration. Erasure is not applicable.
4.5.1B Interrogation
Interrogation of ECT is not applicable.
4.5.2 Invocation and operation
4.5.2.1 Actions at the transferor UE
A UE that has initiated an emergency call, shall not perform any transfer operation involving the dialog associated with
the emergency call.
A UE that initiates a transfer operation shall if the Contact address of the transferee is a GRUU:
- issue a REFER outside an existing dialog as specified in RFC 3515 [2] as updated by IETF RFC 6665 [14] and
IETF RFC 7647 [16], where:
a) the request URI shall contain the SIP URI of the transferee as received in the Contact header field:
b) the Refer-To header field shall indicate the public address of the transfer target;
c) in case of Consultative transfer, the transferor UE has a consultation communication with the transfer target,
a Replaces header field parameter shall be added to the Refer-To URI together with a Require=replaces
header field parameter;
d) the Referred-By header field can be used to indicate the identity of the transferor. When privacy was required
in the original communications dialog and a Referred-By header field is included, the UE shall include a
Privacy header field set to "user
...