9.3 Service provided by the SM‑RL

23.0403GPPRelease 17Technical realization of the Short Message Service (SMS)TS

9.3.1 General

The Short Message Relay Layer (SM‑RL) provides a service to the Short Message Transfer Layer (SM‑TL). This service enables the SM‑TL to send Transfer Protocol Data Units (TPDUs) to its peer entity, receive TPDUs from its peer entity and receive reports about earlier requests for TPDUs to be transferred.

In order to keep track of TPDUs and reports about those TPDUs, primitives between the SM‑TL and SM‑RL contain a Short Message Identifier (SMI), which is a reference number for the TPDU associated with the primitive. This Short Message Identifier is not carried via the SM‑RL protocol of clause 9.3.2. It is carried via the relay layer service between the SC and GMSC. It is also carried by SM‑RL of 3GPP TS 24.011 [13], between the visited MSC and MS. The parameter is not carried by MAP but is mapped to and from the TCAP dialogue Identifier (see CCITT Recommendation Q.771, "Blue Book" [19]) at the GMSC and the visited MSC (therefore the Message Identifier at the SC/GMSC interface is not the same as at the visited MSC/MS interface).

The SM‑RL communicates with its peer entity by the protocol described in the following clauses.

9.3.2 Protocol element repertoire at SM‑RL

Different protocols are required between different pairs of SM‑RL entities. Those are described in other GSM/UMTS specifications. This clause gives a survey of the different information elements which have to be conveyed between those entities. (Note that the notation of the protocol and information elements may vary between different GSM/UMTS specifications).

The SM‑RL comprises the following 6 protocol elements:

RP‑MO‑DATA for transferring a TPDU from MS to SC

RP‑MT‑DATA for transferring a TPDU from SC to MS

RP‑ACK for acknowledging an RP‑MO‑DATA, an RP‑MT‑DATA or an
RP‑SM‑MEMORY‑AVAILABLE

RP‑ERROR for informing of an unsuccessful RP‑MO‑DATA or an RP‑MT‑DATA transfer attempt

RP‑ALERT‑SC for alerting the SC that the MS has recovered operation (information

sent from the HLR to the SC)

RP‑SM‑MEMORY‑AVAILABLE for notifying the network that the MS has memory available to

accept one or more short messages (information sent from the MS to

the HLR)

9.3.2.1 RP‑MO‑DATA

Basic elements of the RP‑MO‑DATA type.

Abbr.	Reference	P1)	Description
RP‑OA	RP‑Originating‑Address	++‑	Address of the originating MS.
RP‑DA	RP‑Destination‑Address	‑++	Address of the destination SC.
RP‑UD	RP‑User‑Data	+++	Parameter containing the TPDU

1) Provision on the links SC<‑>MSC, MSC<‑>MSC or MSC<->SGSN, and MSC<‑>MS or SGSN<->MS indicated by "xxx", where x may be either "+" or "‑", dependent on whether the parameter is mandatory or not on the respective link.

9.3.2.2 RP‑MT‑DATA

Basic elements of the RP‑MT‑DATA type.

Abbr.	Reference	P1)	Description
RP‑PRI	RP‑Priority‑Request	+‑‑	Parameter indicating whether or not the short message transfer should be stopped if the originator SC address is already contained in the MWD.
RP‑MMS	RP‑More‑Messages‑To‑Send	OO‑	Parameter indicating that there are more messages waiting in the SC
RP‑OA	RP‑Originating‑Address	+++	Address of the originating SC.
RP‑DA	RP‑Destination‑Address	++‑	Address of the destination MS.
RP‑UD	RP‑User‑Data	+++	Parameter containing the TPDU
RP-MTI	RP-Message Type Indicator	O–	Parameter indicating if the TPDU is a SMS Deliver or a SMS Status Report 2)
RP-SMEA	RP-originating SME-Address	O–	Address of the originating SME 2)

1) Provision on the links SC<‑>MSC, MSC<‑>MSC or MSC<->SGSN, and MSC<‑>MS or SGSN<->MS indicated by "xxx", where x may be "+", "‑" or "O", dependent on whether the parameter is mandatory, not present or optional on the respective link.

2) These information elements may be included in the "Send Routing Information for SM" sent by the SMS-GMSC to the HLR.

When transmitted, the RP-SMEA shall take the TP-OA value.

When transmitted, the RP-MTI shall be given the following values:

0 SMS Deliver.

1 SMS Status Report.

This may be used by the HLR to distinguish the two cases in order not to apply any filtering mechanism based on the RP-SMEA value in case of a SMS-Status Report transmission.

9.3.2.3 RP‑ACK

The RP‑ACK contains the RP‑User‑Data which is a parameter containing the TPDU (see clauses 9.2.2.1a and 9.2.2.2a).

9.3.2.4 RP‑ERROR

Basic elements of the RP‑ERROR type.

Abbr.	Reference	P1)	Description
RP‑MSI	RP‑MW‑Set‑Indication	+‑‑	Parameter indicating whether or not the MWI has been up‑dated. 2)
RP‑CS	RP‑Cause	+++	Parameter identifying the error type. The RP‑Cause parameter gives the reason why a short message transfer attempt fails. In practice three relay layer protocols are used ‑ SC to GMSC/IWMSC (see Annex A), MAP (see 3GPP TS 29.002 [15]) and via the radio interface (see 3GPP TS 24.011 [13])
RP‑MSIsdn	RP‑international‑‑MS‑ISDN‑number	+‑‑	MSIsdn‑Alert or IMSI-Alert of the MS, see clause 3.2.7 3)
RP-UD	RP-User-Data	OO O	Parameter containing a TPDU

1) Provision on the links SC<->MSC, MSC<->MSC or MSC<->SGSN, and MSC<->MS or SGSN<->MS indicated by "xxx", where x may be "+", "-" or "O" dependent on whether the parameter is mandatory, not present or optional on the respective link.

2) Only present when the RP‑ERROR is transferred from the SMS‑GMSC to the SC.

3) Only present when the RP‑MT‑DATA transfer attempt failed because the MS is not reachable or because the MS memory capacity was exceeded and the MSIsdn‑Alert or IMSI-Alert is different from the MSIsdn or IMSI used by the SC to address the recipient MS.

9.3.2.5 RP‑ALERT‑SC

Basic elements of the RP‑ALERT‑SC type:

Abbr.	Reference	P1)	Description
RP‑MSIsdn	RP‑International‑MS‑ISDN‑Number	O	MSIsdn of the MS.
RP‑IMSI	RP‑International‑Mobile‑Subscriber‑Identity	O	IMSI of the MS

1) Provision; Optional (O).

2) It is mandatory to include either RP-MSIsdn or RP-IMSI.

9.3.2.6 RP‑SM‑MEMORY‑AVAILABLE

Basic elements of the RP‑SM‑MEMORY‑AVAILABLE type:

Abbr.	Reference	P1)	Description
RP‑IMSI	RP‑International‑Mobile‑Subscriber‑Identity	++‑	IMSI of the MS.

1) Provision on the links HLR<‑>VLR or HLR<->SGSN, VLR<‑>MSC and MSC<‑>MS or SGSN<->MS indicated by "xxx", where x may be either "+" or "‑", dependent on whether the parameter is mandatory or not present on the respective link.