ETSI TS 123 204 V16.0.0 (2020-11)

Universal Mobile Telecommunications System (UMTS); LTE; Support of Short Message Service (SMS) over generic 3GPP Internet Protocol (IP) access; Stage 2 (3GPP TS 23.204 version 16.0.0 Release 16)

RTS/TSGS-0223204vg00

General Information

• Status: Not Published
• Technical Committee: 3GPP SA 2 - Architecture
• Current Stage: 12 - Completion
• Completion Date: 18-Nov-2020

Standards Content (Sample)

TECHNICAL SPECIFICATION
Universal Mobile Telecommunications System (UMTS);
LTE;
Support of Short Message Service (SMS) over generic 3GPP
Internet Protocol (IP) access;
Stage 2
(3GPP TS 23.204 version 16.0.0 Release 16)

3GPP TS 23.204 version 16.0.0 Release 16 1 ETSI TS 123 204 V16.0.0 (2020-11)

Reference
RTS/TSGS-0223204vg00
Keywords
LTE,UMTS
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3GPP TS 23.204 version 16.0.0 Release 16 2 ETSI TS 123 204 V16.0.0 (2020-11)
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Legal Notice
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3GPP TS 23.204 version 16.0.0 Release 16 3 ETSI TS 123 204 V16.0.0 (2020-11)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 Void . 8
4a Architecture Requirements . 8
4a.1 General . 8
4a.2 Transport-level interworking . 9
4a.3 Service-level interworking . 9
4a.4 SMS without MSISDN . 10
4a.5 SMS without MSISDN interworking with Non-supporting MSISDN-less SMS UE. 10
5 Architecture model and reference points . 11
5.1 Reference architecture . 11
5.2 Reference points . 11
5.2.1 General . 11
5.2.2 C/S6c interface . 12
5.2.3 Interface between the IP-SM-GW and the HLR/HSS . 12
5.2.4 E/Gd/Gdd/SGd interface . 12
5.2.5 ISC interface . 12
5.2.6 Void . 12
5.3 Functional entities . 12
5.3.1 IP-Short-Message-Gateway (IP-SM-GW) . 12
5.3.1.1 General . 12
5.3.1.2 Transport-level interworking. 13
5.3.1.3 Service-level interworking . 14
5.3.2 HSS/UDM . 14
6 Procedures . 15
6.0 General . 15
6.0a SMS without MSISDN in IMS . 15
6.0a.1 MO-SMS without MSISDN in IMS . 15
6.0a.2 MT-SMS without MSISDN in IMS . 15
6.1 Registration procedure . 16
6.2 De-registration procedure . 17
6.2.1 UE initiated . 17
6.2.2 Network initiated . 17
6.3 Transport-level interworking: Successful encapsulated Short Message origination procedure with
MSISDN . 18
6.3a Transport-level interworking: Short Message origination procedure without MSISDN . 19
6.3a.1 Initial delivery of SMS without MSISDN . 19
6.3a.2 Subsequent re-delivery of SMS without MSISDN . 20
6.4 Transport-level interworking: Successful encapsulated Short Message termination procedure from
SMS-GMSC . 21
6.4a Transport-level interworking: Short Message termination procedure without MSISDN from IMS
network . 23
6.5 Transport-level interworking: Delivery Report procedure . 24
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6.5a Unsuccessful SM termination procedure . 24
6.5b Alert Service Centre procedure when UE is available . 27
6.6 Transport-level interworking: Alert service centre procedure when memory capacity is available . 28
6.7 Service-level Interworking: IM or CPM capable UE sends an Instant Message to an SMS user . 29
6.8 Interaction between transport-level and service-level Interworking . 30
6.8.1 General . 30
6.8.2 IMS Originating . 30
6.8.3 IMS Terminating . 32
6.9 Service-level Interworking: Concatenated Short Messages delivered as a large Instant Message . 32
6.10 Service-level interworking: Status Report procedure for Instant Message to Short Message interworking. 35
6.11 IM or CPM user sends an Instant Message to an SMSIP UE . 36
6.12 Delivery report for an Instant Message delivered as encapsulated Short Message . 37
6.13 Service-level interworking: IM or CPM capable UE sends an Instant Message to an SMS user with
Interworking in the terminating side . 38
6.14 Service-level interworking: IM or CPM user receives Short Message from an SMS user . 39
6.15 Service-level Interworking: CPM capable UE sends a Chat session invitation to an SMS user . 41
6.15.1 IP-SM-GW in the originating network . 41
6.15.2 IP-SM-GW in the terminating network . 43
6.16 Service-level Interworking: CPM capable UE tearing down a Chat session between a CPM user and an
SMS user . 45
6.16.1 IP-SM-GW in the originating network . 45
6.16.2 IP-SM-GW in the terminating network . 45
6.17 Service-level Interworking: SMS user requesting the IP-SM-GW to tear down the Chat session between
a CPM user and an SMS user . 47
6.17.1 IP-SM-GW in the originating network . 47
6.17.2 IP-SM-GW in the terminating network . 47
6.18 Service-level interworking: Status Report procedure for chat session message to Short Message
interworking . 49
Annex A (informative): Service-level interworking: IM or CPM user sends an Instant
Message to a group list including SMS users . 51
Annex B (informative): Group chat sessions . 53
B.1 Service-level interworking: IM or CPM user initiates a group chat and sends an Instant Message
to a group list including SMS users . 53
B.2 Service-level interworking: CPM user extends a one-to-one chat session into a group chat session . 56
B.3 Service-level interworking: IP-SM-GW informs SMS users about group chat participant changes . 57
Annex C (informative): Change History . 59
History . 60

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Foreword
This Technical Specification has been produced by the 3rd 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
The Short Message Service (SMS) has have enjoyed great success in cellular networks. At the same time, specifications
have been and are being developed for extending 3GPP services to non-cellular IP Connectivity Access Networks (IP-
CANs). In this same spirit, this specification describes the capabilities needed to support SMS for generic IP-CANs.
SMS over generic IP access can be used to support applications and services that use SMS when a generic IP access is
used.
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1 Scope
The present document specifies the new capabilities and enhancements needed to support SMS over a generic IP
Connectivity Access Network (IP-CAN) using IMS capabilities (TS 23.228 [9]). These include (but are not limited) to:
1 Enhancements to the HSS;
2 Communication between the SMS-GMSC/SMS-IWMSC and the HSS;
3 Authentication of service usage and registration;
4 Transfer of UE Terminated SMS, UE Originated SMS, and Delivery reports;
5 Mechanisms to handle SMS when there is more than one IP connection active with the UE, etc.
6 Mechanisms to handle MT-SMS without MSISDN to IMS UE, and SMS between IMS UEs that support
MSISDN-less SMS operation.
The document also specifies the capabilities and enhancements needed to support the service level interworking for the
Short Message service as defined in the TS 23.040 [2] and in this specification and the Instant Messaging service as
defined in OMA-TS-SIMPLE_IM-V1_0 [12]. The features supported from the IM specification are limited to the
exchange of short or large immediate messages in pager mode.
NOTE: The page-mode immediate message as defined in TS 24.247[14] is considered as a subset of OMA-TS-
SIMPLE-IM-V1_0 [12].
The document also specifies the capabilities and enhancements needed to support service level interworking for the
Short Message service, as defined in the TS 23.040 [2] and in this specification and the OMA CPM service as defined
in OMA-TS-CPM_Conv_Fnct-V1_0 [17]. The features supported from the CPM specification are the exchange of short
or large immediate messages in pager mode, as well as session-based messaging.
The service requirements are described in TS 22.340 [18].
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] 3GPP TS 23.040: "Technical realization of the Short Message Service (SMS) Point to Point (PP)".
[3] Void.
[4] Void.
[5] Void.
[6] 3GPP TS 29.002: "Mobile Application Part (MAP) specification".
[7] Void.
[8] Void.
[9] 3GPP TS 23.228: "IP Multimedia Subsystem (IMS); Stage 2".
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[10] Void.
[11] Void.
[12] OMA-TS-SIMPLE_IM-V1_0: "Instant Messaging using SIMPLE",
http://www.openmobilealliance.org/.
[13] IETF RFC 5438: "Instant Message Disposition Notification", February, 2009.
[14] 3GPP TS 24.247: "Messaging service using the IP Multimedia (IM) Core Network (CN)
subsystem; Stage 3".
[15] OMA-RD-CPM-V1_0: "CPM Requirements", http://www.openmobilealliance.org/.
[16] OMA-AD-CPM-V1_0: "CPM Architecture", http://www.openmobilealliance.org/.
[17] OMA-TS-CPM_Conv_Fnct-V1_0: "CPM Conversation Functions",
http://www.openmobilealliance.org/.
[18] 3GPP TS 22.340: "IP Multimedia System (IMS) messaging; Stage 1".
[19] IETF RFC 4975: "The Message Session Relay Protocol (MSRP)", September 2007.
[20] 3GPP TS 23.682: "Architecture enhancements to facilitate communications with packet data
networks and applications".
[21] 3GPP TS 23.060: "General Packet Radio Service (GPRS); Service description; Stage 2".
[22] 3GPP TS 23.272: "Circuit Switched (CS) fallback in Evolved Packet System (EPS); Stage 2".
[23] 3GPP TS 23.501: "System Architecture for the 5G System; Stage 2".
[24] 3GPP TS 23.502: "Procedures for the 5G System; Stage 2".
3 Definitions 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
definitions apply. A term defined in the present document takes precedence over the definition of the same term, if any,
in TR 21.905 [1]:
Converged IP Messaging: as defined in OMA-RD-CPM-V1_0 [15]. Converged IP Messaging supports one-to-one,
one-to-many personal communications, and also communication with Applications.
CPM Message: as defined in OMA-RD-CPM-V1_0 [15]: Information that is sent to one or more recipients. A CPM
Message can contain several discrete Media (e.g. text, images, audio-clips, video-clips).
CPM AS: An application server supporting the functionality of a CPM Participating Function and/or a CPM
Controlling Function as defined in OMA-RD-CPM-V1_0 [15].
IM origination: origination of an Instant Message by an IMS UE.
IM termination: termination of an Instant Message by an IMS UE.
IMS core: refers to the core session control elements of the IM CN Subsystem, i.e. the CSCFs, and the IBCF.
Instant Message: an Instant Message as defined in the OMA-TS-SIMPLE_IM-V1_0 [12] and TS 24.247 [14]. The
term Instant Message is also used to designate a CPM Message.
Interworking Selection Function: as defined in OMA-AD-CPM-V1_0 [16]. The Interworking Selection Function
selects an Interworking Function that should perform the actual interworking between CPM and SMS.
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MSISDN-less SMS operation: operation to support SMS communication without the need of MSISDN in the UE's
IMS subscription profile.
MSISDN-less Correlation ID: information element which consists of Receiver Identity (i.e. SIP-URI of B party),
Sender Identity (i.e. SIP-URI of A party), and HLR Identity (i.e., HLR that serves the B party).
Non-supporting MSISDN-less SMS UE: a UE which does not support MSISDN-less SMS operation as defined in this
specification.
SIMPLE IM service: the Instant Messaging Service as defined in the OMA-TS-SIMPLE_IM-V1_0 [12].
SM origination: origination of a Short Message (including SMS over IP) by an SMS capable UE, as defined in
TS 23.040 [2] and this specification.
SM termination: termination of a Short Message (including SMS over IP) by an SMS capable UE, as defined in
TS 23.040 [2] and this specification.
SMS: the Short Message Service as defined in the TS 23.040 [2].
SMSF: the SMS Function as defined in TS 23.501 [23].
SMSIP MESSAGE: an immediate message as defined in TS 23.228 [9], which encapsulates a SM in its text body.
SMSIP UE: a UE which supports SMSIP MESSAGE.
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply:
CPM Converged IP Messaging
IM Instant Message
IMDN Instant Message Disposition Notification
IP-SM-GW IP-Short-Message-Gateway
ISF Interworking Selection Function
SM Short Message
4 Void
4a Architecture Requirements
4a.1 General
The SMS-IP architecture supports the following:
- Notification shall be sent to the HSS that a previously unreachable UE is now reachable.
- Functionality is required to be able to select the domain for message delivery between IMS and CS/PS, and to
have the message delivered to the selected domain.
- Functionality is required to determine whether to transform the message format or not, and to perform the
transformation of the message format when determined.
- The interworking function shall generate the appropriate charging-related information and provide the
appropriate online charging mechanism (if it is applied for the Short Message Service and/or SIMPLE IM
services and/or CPM based services) for the interworking services.
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4a.2 Transport-level interworking
For transport-level interworking , the architecture allows for the following:
- A registration and de-registration mechanism shall be supported where UEs are required to explicitly indicate
their ability to send and receive encapsulated Short Messages.
- It shall provide for the transport of Short Message Service TP layer PDUs (TS 23.040 [2]) and associated RP
layer information.
4a.3 Service-level interworking
For service-level interworking, the architecture allows for the following:
- The service-level interworking is a value added service which requires service subscription. In addition, it shall
also take the operator's policy, if available, into account, e.g. checking on the barring setting of the subscriber to
determine whether to provide this interworking or not, so the service authorisation shall be supported before the
interworking is executed.
- The service-level interworking applies as a fallback only if the users cannot communicate with each other using
their chosen messaging service according to the user preference and operator policy. The location of the
interworking service can be in the originating network and in the terminating network.
- The service-level interworking shall support interworking between OMA SIMPLE IM service as defined in
OMA-TS-SIMPLE_IM-V1_0 [12] and Short Message Service, as defined in the TS 23.040 [2] and in the current
specification.
- The service-level interworking shall support interworking between OMA CPM service as defined in OMA-TS-
CPM_Conv_Fnct-V1_0 [17] and Short Message Service, as defined in the TS 23.040 [2] and in the current
specification.
- The service-level interworking shall take the capability of the terminating UE into account when possible.
- The service level interworking shall be transparent to the end user.
- The service-level interworking shall minimize the impact on the IMS architecture.
- The service-level interworking shall not impact existing functionality of the Short Message Service as described
in TS 23.040 [2] or of the SIMPLE IM service enabler as described in OMA-TS-SIMPLE_IM-V1_0 [12] or of
the CPM service enabler as described in OMA TS CPM_Conv_Fnct-V1_0 [17]. Existing security mechanisms
for the SIMPLE IM service, the Converged IP Messaging service and the Short Message Service shall be reused.
- The interworking function shall be aware if the message should be interworked or not, e.g. specific types of
Short Messages such as an over the air configuration message, shall not be interworked at service-level, but shall
be instead transported as a Short Message via IMS, CS or PS.
- If an SMS user requests an SMS status report that the message was delivered to the recipient, then an SMS status
report shall be generated when the message is delivered using Instant Message.
- If an IMS user requests a notification that the message was delivered to the recipient and the Instant Message is
interworked to Short Message on the originating side, an SMS status report shall be interworked to a delivery
notification when the message is delivered.
- The interworking functionality shall be executed in the following cases:
- Originating network:
- The sender is an IM user or a CPM user who has subscribed to the interworking function and the recipient
is not routable in IMS;
- The operator policy on the originating side has been set to send the Instant Messages via Short Message
Service.
- Terminating network:
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- The user preferences and/or the operator policy of the recipient have been set to receive the incoming
Instant Messages via Short Message Service;
- The received message is a Short Message and the recipient is an IM user or a CPM user and has
subscribed to the interworking service.
NOTE: For ensuring the integrity of the response messages from the IM UE or the CPM UE, it is strongly
recommended that in networks where the IP-SM-GW is deployed, no intermediate nodes modify or
terminate the message between the IP-SM-GW and the terminating IM UE or CPM UE. If intermediate
nodes are deployed, they can send response messages that do not reflect the final response from the IM
UE or CPM UE. Final responses from the IM UE or CPM UE are necessary to ensure correct charging
and delivery reports on the Short Message Service side.
4a.4 SMS without MSISDN
For SMS without MSISDN interworking, the architecture allows for the following in addition to clause 4a.2:
- It shall provide for the transport of Mobile Terminating Short Message Service to UE without the need of
MSISDN in the UE's IMS subscription profile.
- It shall provide for the transport of Mobile Originating Short Message Service from IMS UE that supports
MSISDN-less SMS operation to other IMS UE.
4a.5 SMS without MSISDN interworking with Non-supporting
MSISDN-less SMS UE
This version of the specification does not require the support of SMS communication between IMS UE that supports
MSISDN-less SMS operation as defined in this specification and non-supporting MSISDN-less SMS UE.
NOTE: It is up to implementation on the IMS network that supports the MSISDN-less SMS operation to
determine how to interwork with non-supporting MSISDN-less SMS UE if required.
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5 Architecture model and reference points
5.1 Reference architecture
Figure 5.1 below shows the overall architecture for providing SMS over a generic IP CAN.

SME
SC
SMS-GMSC / SMS-IWMSC HSS
CGF / CDF C / S6c
Rf E / Gd / Gdd / SGd
Sh
OCS Ro IP-SM-GW
J / S6c
ISC
IMS Core
S-CSCF Cx
Mw
P-CSCF
Gm
UE
Figure 5.1: Architecture for providing SMS over a generic IP-CAN
NOTE: Nodes specific to the CPM functions such as ISF are either collocated with the IP-SM-GW or else are not
shown.
5.2 Reference points
5.2.1 General
The clauses below describe the needed enhancements and specific considerations to existing interfaces in order to
support SMS over a generic IP-CAN.
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5.2.2 C/S6c interface
The C or S6c interface allows the SMS-GMSC, using MAP or a Diameter based protocol, to obtain the address of the
IP-Message-GW via mechanisms described in clause 5.3.
5.2.3 Interface between the IP-SM-GW and the HLR/HSS
The interface(s) between the IP-SM-GW and the HLR/HSS is used for:
- Supporting the registration and de-registration from the IP-SM-GW to the HLR/HSS for SMS delivery.
- Forwarding of the Send Routeing Information for Short Message requests from HLR/HSS to IP-SM-GW in
order to return the address where the SM should be forwarded.
- Interrogating the HLR/HSS using Send Routeing Information for Short Message to retrieve the IMSI and the
current MSC, SGSN, MME and/or SMSF addresses.
- Informing the HLR/HSS when a memory capacity exceeded condition ceases.
- Retrieving SMS related data from the HLR/HSS: subscriber data of the short message service similar to the data
for the current CS/PS domain and additional service data on the service authorisation of the encapsulated short
message delivery via IMS, SC address for service-level interworking from Instant Message to Short Message if
the SC address is stored in the HLR/HSS.
Both a Sh interface and either a J or S6c interface can be deployed between the IP-SM-GW and the HLR/HSS. During
the functional allocation the change on existing MAP functions, when used, should be minimized. The deployment of
the J or S6c interface is mandatory, since it is used for forwarding the SRI for SM message.
5.2.4 E/Gd/Gdd/SGd interface
The E/Gd/Gdd/SGd interface allows the IP-SM-GW to connect to the SMS-GMSC, appearing to the SMS-GMSC as an
MSC, SGSN, MME or SMSF.
For interworking with SMS in MME as defined in TS 23.272 [22], Annex C, an IWF may be used as described in that
clause.
For interworking with an SGSN supporting the Gdd interface, an IWF may be used as described in TS 23.060 [21].
5.2.5 ISC interface
The ISC interface allows the IP-SM-GW to forward the receiving message to the SIP based UE via IMS core.
5.2.6 Void
5.3 Functional entities
5.3.1 IP-Short-Message-Gateway (IP-SM-GW)
5.3.1.1 General
The IP-SM-GW shall provide the protocol interworking for delivery of the short message between the IP-based UE and
the SMS-SC. The message is routed to the SMS-SC for delivery to the SMS-based user or the message is received from
the SMS-SC of an SMS-based UE for delivery to an IP-based UE.
The general functions of the IP-SM-GW are:
- to determine the domain (CS/PS or IMS) for delivery of a Short Message;
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- to connect to the SMS-GMSC using established MAP or Diameter based protocols, appearing to the
SMS-GMSC as an MSC, SGSN, MME or SMSF using the E, Gd/Gdd or SGd interfaces;
- to respond to Send Routeing Information for Short Message requests made by the SMS-GMSC, and forwarded
from the HSS, with its own address;
- to connect to the SMS-IWMSC using established MAP or Diameter based protocols, appearing to the SMS-
IWMSC as an MSC, SGSN, MME or SMSF using the E, Gd/Gdd or SGd interfaces;
- to connect to the HSS using established MAP or Diameter based protocols , to obtain the address of
MSC/SGSN/MME/SMSF address(es) for SM termination in CS/PS;
NOTE: The IP-SM-GW need not support all of the functionality defined in MAP in TS 29.002 [6].
- to acquire and maintain knowledge of the association between the MSISDN, IMSI and the address of the
S-CSCF serving of the user;
- to check that it has a valid address in SMS for the sender as well as the recipient when receiving an IMS message
for an SMS user. The IP-SM-GW shall obtain a valid address for both from the SIP headers of the IMS message
(e.g. the sender would be identified in the asserted id in form of TEL URI);
- for terminating procedures:
- if TEL URI is available, it maps the recipient's address from an MSISDN/IMSI to TEL URI format when
receiving an SMS for an IP-based UE, and then it is the responsibility of the IMS core to perform any further
mapping towards a SIP URI as required;
- if TEL URI is not available, it maps the recipient's address from an IMSI to SIP URI format when receiving
an SMS for an IP-based UE.
- to act as an Application Server towards the IMS core;
- to perform domain selection to choose the appropriate domain to deliver a message to a recipient and to obtain
the MSC, SGSN, MME and/or SMSF addresses from the HSS; and
- to manage flags indicating user availability for SMS termination in the HSS and in IP-SM-GW.
- for MSISDN-less SMS operation:
- if the recipient is not addressed with MSISDN but with SIP-URI, the originating IP-SM-GW sends the SM
toward to the target IMS network,
- if delivery to target UE failed, the terminating IP-SM-GW returns MSISDN-less correlation ID to allow the
originating IMS network to retry later,
- if originating IP-SM-GW receives temporary delivery failure with MSISDN-less correlation ID from target
IMS network, it forwards the SM along with the MSISDN-less correlation ID to SMSC for store and
forwarding.
5.3.1.2 Transport-level interworking
The additional functions of the IP-SM-GW when interworking is done by carrying encapsulated Short Messages in IMS
messages are:
- to communicate with the UE using IMS messaging as transport while maintaining the format and functionality of
the Short Message;
- to carry the SMS status messages as encapsulated bodies of IMS messages;
- to store the subscriber data of the short message service similar to the data for the current CS/PS domain and to
perform the short message authorization as performed by the MSC/SGSN/MME/SMSF, as well as to store
additional service data on the service authorisation of the encapsulated Short Message delivery via IMS and to
perform the service authorization.
ETSI
3GPP TS 23.204 version 16.0.0 Release 16 14 ETSI TS 123 204 V16.0.0 (2020-11)
NOTE 1: The short message subscriber data of the CS/PS domain and additional service data on the authorisation
of encapsulated Short Message delivery via IMS are retrieved from the HLR/HSS via third party
registration procedure as specified in the clause 6.1. The IP-SM-GW can request the HSS to send a
notification whenever the subscriber data and/or additional service data is updated, which the IP-SM-GW
can then retrieve.
NOTE 2: The mechanism for prioritizing whether the short message is delivered via a GSM/UMTS or other
IP-CAN connection when the terminal is simultaneously connected to both access networks is outside the
scope of this specification.
5.3.1.3 Service-level interworking
The additional functions of the IP-SM-GW when service-level interworking is done between Short Messages and
Instant Messages in IMS are:
- to determine whether to transform the message format or not, and to perform the transformation of the message
format when determined.
- to use the SC address retrieved either as part of the subscriber data from the HSS at registration or as provisioned
by configuration, when transforming the Instant Message into Short Message.
- to perform the authorization for service-level interworking.
The additional functions of the IP-SM-GW when service-level interworking is done between Short Messages and CPM
Messages in IMS are the same as functions performed for Instant Messages in IMS and additionally:
- to translate a chat session invitation to a short message including instructions for the SMS user how to react
(accept/reject) the chat session invitation, if operator policy mandates the consent of the SMS user. Otherwise
the IP-SM-GW shall respond a chat session invitation on behalf of the SMS user (accept/reject), according to
operator policy;
- to translate the SMS user's answer to a chat session invitation to a proper response for the chat session invitation
request;
- to inform SMS user about the changes of group chat session parameters;
- to translate a chat session teardown request to a short message, if operator policy mandates it; and
- to translate the SMS user's request to leave a chat session to a proper CPM request.
5.3.2 HSS/UDM
In order to support SMS over generic IP access, the HSS/UDM shall support the following functions:
- storing the pre-configured address of the IP-SM-GW on a subscriber basis;
NOTE: If all subscribers are assigned to a single IP-SM-GW address, the IP-SM-GW address does not need to be
pre-configured in the HSS.
- handling an indication that the terminal is registered with an IP-SM-GW for delivery of SMS;
- storing the SMSF address when the SMSF registers with the UDM as specified in TS 23.502 [24];
- responding to the "send routing information for short message" query from IP-SM-GW with the address of the
MSC/SGSN/MME/SMSF;
- forwarding the Send Routeing Information for Short Message, from an SMS-GMSC, towards the IP-SM-GW
and forwarding any responses to the originator of the Send Routeing Information for Short Message;
- returning the IMSI and the MSC, SGSN, MME and/or SMSF addresses as a response to Send Routeing
Information for Short Message required from IP-SM-GW;
- alerting the SCs stored in the message waiting data when the terminal is registered with an IP-SM-GW for
delivery of short message;
ETSI
3GPP TS 23.204 version 16.0.0 Release 16 15 ETSI TS 123 204 V16.0.0 (2020-11)
- reporting notification to the IP-SM-GW of the reachability of a UE at the transport layer after a delivery failure;
- accepting delivery status reports from IP-SM-GWs instead of SMS-GMSC.
6 Procedures
6.0 General
The clause describes the procedures for the support of transport-level interworking between Short Message service and
encapsulated Short Message via IP service, for the support of the service-level interworking for the Short Message
service and Instant Messaging service as defined in OMA-TS-SIMPLE_IM-V1_0 [12], for the support of the service-
level interworking for the Short Message service and Converged IP Messaging service as defined in OMA-TS-
CPM_Conv_Fnct-V1_0 [17] and for the support of receiving MT-SMS to a UE without MSISDN. Clauses only
applying to either transport-level interworking or service-level interworking are indicated as such.
NOTE: In the procedures in the following clauses, the I-CSCF, P-CSCF and ASs such as IM AS, as well as nodes
specific to CPM functions such as ISF, are not shown in the figures.
6.0a SMS without MSISDN in IMS
6.0a.1 MO-SMS without MSISDN in IMS
For MO-SMS without MSISDN, the IP-SM-GW of the originating side fills the RP-OA field with a value that indicates
UE is MSISDN-less to satisfy the protocol requirement. If the originating UE does not have MSISDN or the recipient
UE is addressed with SIP-URI (i.e., recipient is not addressed with MSISDN) then IP-SM-GW first tries to deliver the
SMS d
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