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TECHNICAL REPORT
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
IMS Multimedia Telephony service;
and supplementary services
(3GPP TR 22.973 version 15.0.0 Release 15)
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3GPP TR 22.973 version 15.0.0 Release 15 1 ETSI TR 122 973 V15.0.0 (2018-07)
Reference
RTR/TSGS-0122973vf00
Keywords
GSM,LTE,UMTS
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3GPP TR 22.973 version 15.0.0 Release 15 2 ETSI TR 122 973 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
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Foreword
This Technical Report (TR) 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 "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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Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
3 Definitions, symbols and abbreviations . 6
3.1 Definitions . 6
3.2 Abbreviations . 7
4 Service description . 7
4.1 General service characteristics . 7
4.2 Default media handling capabilities of the IMS Multimedia Telephony service . 7
5 Service requirements . 8
6 Quality of Service (QoS) . 8
7 Interworking considerations . 8
7.1 Interworking with CS domain . 8
7.2 Interworking with external networks . 8
8 Supplementary services . 8
8.1 Background . 8
8.1.1 General considerations on supplementary services in IMS . 8
8.1.2 IMS services . 8
8.1.3 Supplementary services . 8
8.1.4 'Building blocks' of supplementary services . 9
8.1.5 Service consistency with CS supplementary services . 9
8.2 Comparisons between CS supplementary services and existing IMS capabilities . 10
8.2.1 Line Identification services . 10
8.2.1.1 CLIP . 10
8.2.1.2 CLIR . 11
8.2.1.3 COLP . 11
8.2.1.4 COLR . 11
8.2.2 Call Forwarding . 12
8.2.3 Call Waiting and Call Hold . 13
8.2.3.1 Call Waiting . 13
8.2.3.2 Call Hold . 13
8.2.4 Call Barring . 13
8.3 Analysis of TISPAN Multimedia Telephony supplementary services . 14
8.3.1 Analysis result . 18
8.3.1.1 Originating Identification Presentation (OIP) . 18
8.3.1.2 Originating Identification Restriction (OIR) . 18
8.3.1.3 Terminating Identification Presentation (TIP). 18
8.3.1.4 Terminating Identification Restriction (TIR) . 18
8.3.1.5 Communication Diversion (CDIV) . 18
8.3.1.6 Communication Hold (HOLD) . 19
8.3.1.7 Communication Barring (CB) . 19
8.3.1.8 Message Waiting Indication (MWI) . 19
8.3.1.9 Conference (CONF) . 19
8.3.1.10 Explicit Communication Transfer (ECT) . 19
8.4 Potential supplementary service not described by TISPAN . 19
8.4.1 Service interactions with other supplementary services . 19
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9 Conclusion . 20
Annex A: Change history . 21
History . 22
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Foreword
rd
This Technical Report 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.
Introduction
In addition to reusing the IMS system as defined by 3GPP, TISPAN is defining an IMS based Multimedia Telephony
service, which is an evolution of the CS based Telephony service provided by traditional ISDNs and PSTNs [2].
A similar service, defined by 3GPP, is needed for wireless access to IMS, in order to be able to define services to the
end-users, and to support interoperability in multi-vendor and multi-operator environment and to provide the user with
the same experience across the different IP based accesses and domains
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1 Scope
This Technical Report defines the IMS Multimedia Telephony service and associated supplementary services for IMS.
It aims to take account and build on the IMS capabilities already provided in 3GPP Release 5 and Release 6.
The objective is to define the minimum set of capabilities required in the IP Multimedia Subsystem to secure multi-
vendor and multi-operator inter-operability for the IMS Multimedia Telephony service and related Supplementary
Services.
Close cooperation shall be sought with TISPAN. TISPAN requirements, as captured in [2], will be taken into account,
and referred to where appropriate.
While the user experience for the IMS Multimedia Telephony service is expected to have some similarity to existing
telephony services, the richer capabilities of IMS will be exploited.
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 TR 21.905: "Vocabulary for 3GPP Specifications".
[2] ETSI TS 181 002: " Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Multimedia Telephony with PSTN/ISDN simulation services",
version 1.1.1.
[3] ETSI TS 181 001: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Videotelephony over NGN; Stage 1 service description".
[4] 3GPP TS 22.228: "Service requirements for the Internet Protocol (IP) multimedia core network
subsystem (IMS); Stage 1".
[5] 3GPP TR 23.816: "Identification of communication services in IMS".
Note: Reference [5] is an internal report to 3GPP, available via
http://www.3gpp.org/ftp/Specs/html-info/23816.htm
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in TR 21.905 [1] and the following apply. A
term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 [1].
(none)
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3.2 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply. An
abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in
TR 21.905 [1].
(none)
4 Service description
4.1 General service characteristics
The IMS Multimedia Telephony service should allow multimedia conversational communications between two or more
users. It provides real time bidirectional conversational transfer of speech, video or optionally other types of data.
The IMS Multimedia Telephony service is point to point between terminals communicating , or a terminal and a
network entity. This communication is usually symmetrical, but in special cases the media components present in each
direction may be different, or they may be the same but with different bit rates and Quality of Service.
An IMS Multimedia Telephony service can start with only one type of media and additional types of media may or may
not be added by the users as the communication progress. Therefore a particular IMS Multimedia Telephony service
may consist of only one type of media, e.g. speech.
The IMS Multimedia Telephony service is different from other IMS based services, such as Push to Talk over Cellular
(PoC).
Its characteristics includes the following:
- IMS Multimedia Telephony is a service where speech, and speech combined with other media components, is
the typical usage but the service is not limited to always include speech, it also caters for other media or
combinations of media (e.g. text and video).
- The IMS Multimedia Telephony service includes supplementary services. The behaviour of supplementary
services is almost identical to supplementary services for CS voice (TS 11)
Note: Most supplementary services are active in the set-up phase. Mid session supplementary services such as
session transfer and session hold exist.
- The anticipated usage model is that of traditional telephony: one user connecting to any other user, regardless of
operator and access technology.
4.2 Default media handling capabilities of the IMS Multimedia
Telephony service
The IMS Multimedia Telephony service can support many different types of media and the default set of capabilities
include the following:
- Full duplex speech
- Real time video (simplex, full duplex), synchronized with speech if present.
- Text communication
- File transfer,
- Video clip sharing, picture sharing, audio clip sharing. Transferred files may be displayed/replayed on receiving
terminal for specified file formats.
At least one common standardized format (e.g. JPEG, AMR) shall be supported per media type.
The IMS Multimedia Telephony service should at least support the following handling of media
- Adding and removing individual media to/from a IMS Multimedia Telephony communication
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5 Service requirements
General service requirements as specified for IMS services in [4] apply.
6 Quality of Service (QoS)
General QoS requirements as specified for IMS services in [4] apply.
7 Interworking considerations
7.1 Interworking with CS domain
Standardisation of interworking between the IMS domain and the CS domain for multimedia telephony
communications is provided as specified in [4].
7.2 Interworking with external networks
General interworking requirements with external networks as specified for IMS services in [4] apply.
8 Supplementary services
8.1 Background
8.1.1 General considerations on supplementary services in IMS
With the specification of the IP Multimedia Subsystem (IMS see [4]) 3GPP has created a basis for flexible deployment
of a multitude of IP based services. In contrast to GSM, which defined a set of bearer- and teleservices that were
complemented by a number of supplementary services, 3GPP did not pursue that but rather specified "IP multimedia
sessions" within the concept of IMS.
8.1.2 IMS services
An "IP multimedia session" could carry any combination of media (voice, video, text …) and the services, that make
use of these IMS sessions, need not be standardised. However, in the last years non-3GPP standardisation bodies like
the Open Mobile Alliance (OMA) have created standards for several IMS based services (e.g. PoC, "Presence Simple"
and others)
The user primarily distinguishes, understands and experiences these services, not the sessions therein. For example, PoC
may set up a session, that transports voice in just the same way as a IMS Multimedia Telephony service would, but for
the user these are two different services.
8.1.3 Supplementary services
The user may handle supplementary services to the examples given above differently (e.g. he may choose to hide his
identity in the PoC chat group while still providing it in a IP Multimedia telephone call).
In IMS supplementary services apply to individual services. An IMS service – at least in this respect – can roughly be
considered as the analogoue to the bearer- or teleservices of GSM.
Note: To be able to apply a supplementary service to individual IMS services these services need to be identifiable.
Currently SA2 is working on this task (see [5]).
A single supplementary service, when applied to two different IMS services, may not only have different user-settings,
as in the example above, but even may have different service behaviour. For example when forwarding is applied to an
IMS service, that mimics a voice call, then activating the forwarding would simply forward the call to the intended
destination. But when forwarding is applied to a different, more complex multimedia service, the user may be able to
e.g. only forward the video part to a different destination (e.g. his PDA, that has a bigger screen or to a recording
device) and keep the speech part on his telephone.
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For the reasons described above we can not hope to be able to define supplementary services, that can 'generically' be
applied to IMS services.
8.1.4 'Building blocks' of supplementary services
The approach taken in 3GPP is that IMS provides 'building blocks' such that supplementary services for a particular
IMS service can be constructed from these building blocks.
Staying with the last example we could e.g. define a building block that forwards the speech (or video) component of a
IMS service to a different terminal. Ideally, such a building block would be (re-)usable for any IMS service.
In the following sections it is analyzed, whether these 'building blocks' are sufficient for the purpose of providing the
Supplementary Services, listed in [2] and [3] to the IMS Multimedia Telephony service.
8.1.5 Service consistency with CS supplementary services
The IMS Multimedia Telephony service provides a telephony service and a videotelephony service for the IMS, which
can be considered the equivalent in the IMS of the respective CS based services (Teleservice 11 and Bearerservice 30).
In addition the IMS Multimedia Telephony service specifies a number of supplementary services that provide an almost
identical service experience to the user as the respective CS based supplementary services.
Therefore with the introduction of IMS Multimedia Telephony – unlike 22.228 – the same user may make/receive a
voice (or video) service via two different systems (CS and PS/IMS). Moreover, during an ongoing voice call, Voice
Call Continuity (VCC) may be invoked to enable a smooth transition of the voice call between the two systems.
In the case that VCC has turned a CS voice call into an IMS voice call, this IMS voice call is considered an instance of
the IMS Multimedia Telephony service with a voice component.
Note, that currently, a function like VCC for video calls does not exist.
As CS voice (and video) services have been established for a long time the user will expect the same service behaviour,
whether he places a voice (or video) call via the CS domain or via IMS. Often a user may even not know how his call is
set up. In this case a different service behaviour of the call – one time set-up via the CS domain and at another time via
IMS – would be very annoying.
The following figure depicts this service-interworking.
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8.2 Comparisons between CS supplementary services and
existing IMS capabilities
8.2.1 Line Identification services
8.2.1.1 CLIP
The CLIP service provides presentation of the calling line identity to the called party. In IMS this is technically
provided already using the P-Asserted Identity header.
Comparison of CS-CLIP and IMS capabilities
CS-Domain IMS
Provisioning Users only receive line identity if All IMS users are capable of
CLIP is provisioned receiving line identity
Identity format E.164 number SIP or TEL URL (Tel URL includes
E.164 number)
Override Override capability may be Network behaviour may provide an
provisioned per subscriber. override function to meet local
needs, but there is no standard per-
subscriber provisioning of override.
Interrogation Users may interrogate using a No standard interrogation feature is
standard procedure to determine provided.
the state of their CLIP service
The IMS provides the core CLIP functionality.
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8.2.1.2 CLIR
The CLIR service allows the calling party to restrict the presentation of their identity to the called party. In IMS this is
technically provided using the Privacy header.
Comparison of CS-CLIR and IMS capabilities
CS-Domain IMS
Provisioning Only users provisioned with CLIR All IMS users are capable of
may restrict their identity restricting their identity on a per
session basis.
Temporary mode CLIR can be provisioned in All IMS users are capable of
temporary mode (users select per restricting their identity on a per
call whether to invoke CLIR) or session basis.
permanent mode (CLIR is always
invoked). In temporary mode there Unless requested by the user the
are two options: default is to identity is normally made available
present identity, default is to restrict for presentation.
identity.
Interrogation Users may interrogate using a No standard interrogation feature is
standard procedure to determine provided.
the state of their CLIR service
As can be seen the current IMS behaviour corresponds to the CS-Domain use of CLIR in a temporary mode.
IMS sessions are not intended to be anonymous to the originating or terminating network operators (see [4]). Therefore,
even if a user has requested to withhold his identity both, the originating and terminating network operators are able to
identify the user (e.g. for Lawful intercept purposes, for destination users with override category or Malicious
Communication Identification MCID).
8.2.1.3 COLP
The COLP service provides the calling party with the possibility to receive the line identity of the connected party. In
IMS this is technically provided by the P-Asserted-Identity header in response messages from the connected party.
Comparison of CS-COLP and IMS capabilities
CS-Domain IMS
Provisioning Only users provisioned with COLP All IMS users are capable of
may receive the identity of the receiving the line identity of the
connected party connected party via response
messages to requests
Identity format E.164 number SIP or TEL URL (Tel URL includes
E.164 number)
Override Override capability may be Network behaviour may provide an
provisioned per subscriber. override function to meet local
needs, but there is no standard per-
subscriber provisioning of override.
Interrogation Users may interrogate
...