A.3. IWF related to the S6c interface between HSS and central SMS functions

29.3053GPPInterWorking Function (IWF) between MAP based and Diameter based interfacesRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

A.3.1 Introduction

3GPP TS 23.272 [3] has specified the "SMS in MME" architecture option, where an IWF between the HSS supporting the S6c interface and the central SMS functions (SMS-GMSC, SMS-IWMSC, SMS Router) supporting the MAP C interface for SMS is defined. This S6c IWF is described in the following subclauses.

3GPP TS 23.204 [6] has specified the support of SMS for IMS UE to IMS UE without MSISDN which impacts the IWF description over S6c.

A.3.2 Interworking scenarios

A.3.2.1 IWF scenario

This interworking scenario is illustrated in the two following figures:

– in figure A.3.2.1-1, an IWF is between a HSS supporting the S6c interface based on Diameter and central SMS functions (SMS-GMSC, SMS-IWMSC) supporting a MAP based C interface for SMS. There is no SMS Router.

– in figure A.3.2.1-2, there is a SMS router used for MT SMS with which the IWF will interact, taking into account that Diameter requests from the IWF, according to operator configuration, are sent to the SMS Router either directly or via the HSS.

This IWF scenario can be an inter PLMN use case where the HSS, the SMS Router, the IP-SM-GW and the IWF are in the Home PLMN.

In the Home PLMN, when the HSS supports S6c, the SMS Router shall also support S6c, i.e. there is no IWF between HSS and SMS Router.

This IWF scenario can be an intra PLMN use case.

Figure A.3.2.1-1 S6c – C for SMS interworking scenario with an IWF

Figure A.3.2.1-2 S6c – C for SMS interworking scenario with SMS Router and an IWF

A.3.3 General considerations

A.3.3.1 Routing considerations

MAP requests issued by the SMS-GMSC are routed to the IWF on the basis of the SSN and of the MSISDN, then the corresponding Diameter requests are routed on the basis of the Diameter application identifier and of the MSISDN or of the IMSI. If a SMS router is deployed, the HSS will forward the Send Routing Info for SM commands to the SMS router.

In a retry context of SMS for IMS UE to IMS UE without MSISDN (see 3GPP TS 23.204 [6]), the MAP requests issued by the SMS-GMSC or the SMS-SC are routed to the IWF on the basis of the SSN and of the HSS ID, then the corresponding Diameter requests are routed on the basis of the Diameter application identifier and of the HSS ID. In this case, the HSS does not forward the Send Routing Info for SM commands to the IP-SM-GW.

Diameter requests (i.e when an Alert procedure) issued by the HSS are routed to the IWF on the basis of the application identifier and of the SC-Address AVP containing the SMS-SC number. Then the corresponding MAP request is routed to the SMS-IWMSC on the basis of the SSN and of the SMS-SC number.

A.3.4 The mapping of procedures

A.3.4.1 Send Routing Info for SM

The mapping of the Send Routing Info for SM procedure is shown in figure A.3.4.1-1:

Figure A.3.4.1-1: Mapping of Send Routing Info for SM procedure

1. The IWF receives a sendRoutingInfoForSM MAP V3 message from the SMS-GMSC.

2. The IWF sends SRR to the HSS or SMS Router or IP-SM-GW.

3. The IWF receives SRA from the HSS or SMS Router or IP-SM-GW.

4. The IWF sends a sendRoutingInfoForSM Ack message to the SMS-GMSC.

5. The IWF sends an informServiceCentre message to the SMS-GMSC if the SRA contains information elements requiring to be delivered with an informServiceCentre message and closes the MAP dialog

A.3.4.2 Alert Service Centre

The mapping of the Alert Service Centre procedure is shown in figure A.3.4.2-1:

Figure A.3.4.2-1: Mapping of Alert Service Centre procedure

1. The IWF receives a ALR message from the HSS.

2. The IWF opens a MAP v3 dialogue towards the SMS-IWMSC by sending alertServiceCentre.

3. The IWF receives alertServiceCentre Ack from the SMS-IWMSC.

4. The IWF sends ALA to the MME, SGSN.

A.3.4.3 Report SM Delivery Status

The mapping of the Report SM Delivery Status procedure is shown in figure A.3.4.3-1:

Figure A.3.4.3-1: Mapping of Report SM Delivery Status procedure

1. The IWF receives a reportSM-DeliveryStatus MAP V3 message from the SMS-GMSC or the SMS-SC.

2. The IWF sends RDR to the HSS.

3. The IWF receives SRA from the HSS.

4. The IWF closes the MAP dialogue with the SMS-GMSC by sending a reportSM-DeliveryStatus Ack to the SMS-GMSC or the SMS-SC.

A.3.5 The mapping of parameters

A.3.5.1 Mapping of Parameters for the Send Routing Info for SM Procedure

A.3.5.1.1 RoutingInfoForSM-Arg mapping to SRR

When the IWF needs to construct a SRR command as a result of receiving a MAP sendRoutingInfoForSM message (see subclause A.3.4.1.1 step 2), the IWF shall populate AVPs of SRR as described below:

– MSISDN AVP shall be populated with the value received within the msisdn parameter of RoutingInfoForSM-Arg when available.

– User-Name AVP shall be populated with the value received within the imsi parameter of RoutingInfoForSM-Arg when available.

– SMSMI-Correlation-ID AVP shall be present if correlationID in RoutingInfoForSM-Arg is present and be populated as follows:

– Destination-SIP-URI AVP shall be populated with the value received within the sip-uri-B parameter of RoutingInfoForSM-Arg.

– SM-RP-PRI AVP shall be present and populated with the value received within the sm-RP-PRI parameter of RoutingInfoForSM-Arg.

– SC-Address AVP shall be present and populated with the value received within the serviceCentreAddress parameter of RoutingInfoForSM-Arg

– SM-RP-MTI AVP shall be populated with the value received within the sm-RP-MTI parameter, when present, of RoutingInfoForSM-Arg

– SM-RP-SMEA AVP shall be populated with the value received within the sm-RP-SMEA parameter, when present, of RoutingInfoForSM-Arg

– SRR-Flags AVP: Flags shall be set as follows:

– GPRS-Indicator shall be set to 1 if the gprsSupportIndicator parameter was present within RoutingInfoForSM-Arg; otherwise shall be set to 0 or the AVP shall be absent.

– SM-Delivery-Not-Intended AVP shall be populated with the value received within the sm-deliveryNotIntended parameter, when present, of RoutingInfoForSM-Arg

– Supported-Features AVP shall be absent.

A.3.5.1.2 SRA mapping to RoutingInfoForSM-Res/Error

When the IWF needs to construct a MAP sendRoutingInfoForSM Ack message as a result of receiving a SRA command (see subclause A.3.4.1.1 step 5), the IWF shall populate sub-parameters of RoutingInfoForSM-Res/Error as described below:

RoutingInfoForSM-Res:

– imsi shall be populated with the value received within the User-Name AVP, when present, within SRA.

– Sub-parameters of locationInfoWithLMSI shall be populated as follows:

– networkNode-Number shall be populated with the value received within either the MME-Number-for-MT-SMS AVP or the MSC-Number AVP or the SGSN-Number AVP or the IP-SM-GW-Number AVP, within the Serving-Node when present, within the SRA.

– Sub-parameters diameter-Name and diameter-Realm of networkNodeDiameterAddress shall be populated with the values received within the MME-Name & MME-Realm AVPs or within the IP-SM-GW-Name & IP-SM-GW-Realm AVPs within the Serving-Node AVP when present, within the SRA.

– lmsi shall be populated with the value received within the LMSI AVP when present, within the SRA.

– gprsNodeIndicator shall be set if the received Serving Node AVP contains a SGSN AVP.

– additional-Number shall be populated with the value received within either the MME-Number-for-MT-SMS User-Name AVP or the MSC-Number AVP or the SGSN-Number SGSN AVP, within the Additional-Serving-Node when present, within the SRA.

– Sub-parameters diameter-Name and diameter-Realm of additionalNetworkNodeDiameterAddress shall be populated with the values received within the MME-Name and MME-Realm AVPs within the Additonal-Serving-Node AVP when present, within the SRA.

– sm-RP-UI in MO-ForwardSM-Res shall be populated with the value received within the SM-RP-UI AVP when present.

– extensionContainer in MT-ForwardSM-Res shall be absent.

Error:

Values other than SUCCESS within the Result-Code / Experimental-Result AVP shall be mapped according to the following table:

Table A.3.5.1.2-1 Mapping from Diameter error codes to MAP error codes

Diameter Result code / Experimental Result	MAP error code
DIAMETER_UNABLE_TO_COMPLY	systemFailure
DIAMETER_MISSING_AVP	dataMissing
DIAMETER_INVALID_AVP_VALUE	unexpectedDataValue
DIAMETER_ERROR_FACILITY_NOT_SUPPORTED	facilityNotSupported
DIAMETER_ERROR_USER_UNKNOWN	unknownSubscriber
DIAMETER_ERROR_SERVICE_NOT_SUBSCRIBED	teleserviceNotProvisioned
DIAMETER_ERROR_SERVICE_BARRED	callBarred
DIAMETER_ERROR_ABSENT_USER	absentSubscriberSM

When the Diameter Result code is DIAMETER_ERROR_ABSENT_USER, one or two absent user diagnostics (MME-Absent-User-Diagnostic-SM or MSC-Absent-User-Diagnostic-SM or SGSN-Absent-User-Diagnostic-SM AVPs) may be received. The following additional mapping shall apply:

– When only one absent user diagnostic AVP is received, it is mapped to the absentSubscriberDiagnosticSM parameter.

– When two absent user diagnostics AVPs are received , the SGSN-Absent-User-Diagnostic-SM AVP is mapped to the additionalAbsentSubscriberDiagnosticSM parameter , the other AVP is mapped to the absentSubscriberDiagnosticSM parameter.

A.3.5.1.3 SRA mapping to informServiceCentreArg

When the IWF needs to construct a MAP informServiceCentre message as a result of receiving a SRA command (see subclause A.3.4.1.1 step 4), the IWF shall populate sub-parameters of InformServiceCentreArg as described below:

– storedMSISDN shall be populated with the value received within the MSISDN AVP within the User Identifier AVP, when present, within SRA.

– mw-Status shall be populated with the value received within the MWD-Status AVP, when present, within SRA.

– absentSubscriberDiagnosticSM shall be populated with the value received within

– either the MME-Absent-User-Diagnostic-SM AVP or the MSC-Absent-User-Diagnostic-SM AVP or the SGSN-Absent-User-Diagnostic-SM AVP, when only one of them is present, within the SRA.

– either MME-Absent-User-Diagnostic-SM AVP or the MSC-Absent-User-Diagnostic-SM AVP, if one of them is present and if SGSN-Absent-User-Diagnostic-SM AVP is also present.

– additionalAbsentSubscriberDiagnosticSM shall be populated with the value received within the SGSN-Absent-User-Diagnostic-SM AVP, if it is present and if either the MME-Absent-User-Diagnostic-SM AVP or the MSC-Absent-User-Diagnostic-SM AVP is present , within the SRA.

A.3.5.2 Mapping of Parameters for the Alert Service Centre Procedure

A.3.5.2.1 ALR mapping to alertServiceCentre-Arg

When the IWF needs to construct a MAP alertServiceCentre message as a result of receiving an ALR command (see subclause A.3.4.2 step 2), the IWF shall open a MAP dialogue in application context version 3 and populate sub-parameters of alertServiceCentre-Arg as described below:

– msisdn shall be populated with the value received within MSISDN AVP, when present, within the User-Identifier AVP within ALR.

– imsi shall be populated with the value received within User-Name AVP, when present, within the User-Identifier AVP within ALR.

– serviceCentreAddress shall be present and populated with the value received within the SC-Address AVP within ALR.

– correlationId shall be present if SMSMI-Correlation-ID AVP within ALR is present and be populated as follows:

sip-uri-B parameter shall be populated with the value received within Destination-SIP-URI AVP within SMSMI-Correlation-ID AVP within ALR

A.3.5.2.2 alertServiceCentre-Res / Error mapping to ALA

When the IWF needs to construct an ALA command as a result of receiving a MAP alertServiceCentre Ack/Error message (see subclause A.3.4.2 step 4), the IWF shall populate AVPs of ASA as described below:

Result-Code / Experimental-Result AVP shall be set to:

– DIAMETER_SUCCESS if a MO-ForwardSM-Res parameter was received in the TCAP ResultLast component;

– a DIAMETER base protocol result code according to the following table:

Table A.3.5.2.2-1 Mapping from MAP error codes to Diameter error codes

MAP error code	Diameter Result code / Experimental Result
systemFailure	DIAMETER_UNABLE_TO_COMPLY
dataMissing	DIAMETER_MISSING_AVP
unexpectedDataValue	DIAMETER_INVALID_AVP_VALUE

Supported Features AVP shall be absent.

A.3.5.3 Mapping of Parameters for the Report SM Delivery Status Procedure

A.3.5.3.1 ReportSM-DeliveryStatusArg mapping to RDR

When the IWF needs to construct a SRR command as a result of receiving a MAP reportSM-DeliveryStatus message (see subclause A.3.4.3 step 2), the IWF shall populate AVPs of SRR as described below:

– User-Identifier AVP shall be present and populated as follows:

– MSISDN AVP shall be populated with the value received, after format translation, within the msisdn parameter of ReportSM-DeliveryStatusArg.

– SMSMI-Correlation-ID AVP shall be present if correlationID in ReportSM-DeliveryStatusArg is present and be populated as follows:

– Destination-SIP-URI AVP shall be populated with the value received within the sip-uri-B parameter of ReportSM-DeliveryStatusArg.

– SC-Address AVP shall be present and populated with the value received within the serviceCentreAddress parameter of RoutingInfoForSM-Arg

– SM-Delivery-Outcome AVP shall be present and populated as follows:

SGSN-SM-Delivery-Outcome AVP shall be populated

– with the value received in sm-DeliveryOutcome parameter within ReportSM-DeliveryStatusArg if deliveryOutcomeIndicator flag is present;

– with the value received in additionalSM-DeliveryOutcome, when present, within ReportSM-DeliveryStatusArg;

otherwise SGSN-SM-Delivery-Outcome AVP shall be absent.

MSC-SM-Delivery-Outcome AVP shall be populated

– with the value received in sm-DeliveryOutcome parameter within ReportSM-DeliveryStatusArg if deliveryOutcomeIndicator flag is absent;

otherwise MSC-SM-Delivery-Outcome AVP shall be absent.

MME-SM-Delivery-Outcome AVP shall be absent.

NOTE: the MAP-REPORT-SM-DELIVERY-STATUS request does not differentiate the delivery to a MSC from a delivery to a MME.

IP-SM-GW-Delivery-Outcome AVP shall be populated

– with the value received in sm-DeliveryOutcome parameter within ReportSM-DeliveryStatusArg if ip-sm-gw-Indicator flag is present;

– with the value received in ip-sm-gw-sm-deliveryOutcome, when present, within ReportSM-DeliveryStatusArg;

otherwise IP-SM-GW- Delivery-Outcome AVP shall be absent.

NOTE: The IP-SM-GW- Delivery-Outcome AVP presence can only occur when SMS-GMSC supports T4 triggering.

Supported-Features AVP shall be absent.

A.3.5.3.2 RDA mapping to ReportSM-DeliveryStatusRes/Error

When the IWF needs to construct a MAP reportSM-DeliveryStatus Ack message as a result of receiving a RDA command (see subclause A.3.4. step 4), the IWF shall populate sub-parameters of reportSM-DeliveryStatusRes/Error as described below:

reportSM-DeliveryStatusRes:

– storedMSISDN shall be populated with the value, after format translation, received within the User-Name AVP, when present, within SRA.

– extensionContainer shall be absent.

Error:

Values other than SUCCESS within the Result-Code / Experimental-Result AVP shall be mapped according to the following table:

Table A.3.5.3.2-1 Mapping from Diameter error codes to MAP error codes

Diameter Result code / Experimental Result	MAP error code
DIAMETER_UNABLE_TO_COMPLY	systemFailure
DIAMETER_MISSING_AVP	dataMissing
DIAMETER_INVALID_AVP_VALUE	unexpectedDataValue
DIAMETER_ERROR_USER_UNKNOWN	unknownSubscriber
DIAMETER_ERROR_MWD_LIST_FULL	messageWaitingListFull