10.1 Short message mobile terminated

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

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

The entities involved in this procedure are depicted in figure 14.

NOTE 1: The SMS Router is an optional entity. If it is not present, the two interfaces extending from the right side of the SMS‑GMSC extend directly to the SGSN and MSC, respectively.

NOTE 2: Since the short message mobile terminated procedure covers the functionality required at SM‑RL for transferring TPDUs from SC to MS, the procedure described covers both short message (SMS‑DELIVER) and status report (SMS‑STATUS‑REPORT) transfer. The term "short message transfer" therefore, in this clause, covers both cases.

Figure 14: Interfaces involved in the Short message mobile terminated procedure. GSM TS 43.002 [5]. X is the interface between an MSC and an SC as defined in clause 5

In figure 15, sequence diagrams are shown for the following basic situations of short message mobile terminated transfer attempt:

‑ Successful short message transfer via the MSC or the SGSN;

– Successful short message transfer via the SMS Router, and the MSC or SGSN;

‑ Short message transfer attempt failing due to error at the SMS‑GMSC;

‑ Short message transfer attempt failing due to negative outcome of HLR information retrieval;

– Short message transfer attempt via the SMS Router failing due to negative outcome of HLR information retrieval;

‑ Short message transfer attempt failing due to error at the MSC or SGSN;

‑ Short message transfer attempt failing due to negative outcome of VLR information retrieval;

‑ Short message transfer attempt failing due to erroneous message transfer on the radio path;

‑ Short message transfer attempt failing over the first path (e.g. SGSN) and succeeding over the second path (e.g. MSC);

– Short message transfer attempt via the SMS Router failing over the first path (e.g. SGSN) and succeeding over the second path (e.g. MSC);

‑ Short message transfer attempt failing over the first path (e.g. SGSN) and over the second path (e.g. MSC).

References to the relevant specifications of the different operations are given in clause 4.

NOTE 1): This operation is not used by the SGSN.

Figure 15a): Successful short message transfer attempt via the MSC or the SGSN

Operation 4a: The SMS-GMSC indicates in the ForwardShortMessage the time until which it waits for receiving the Delivery Report.

Operations 4b to 6: If the MS is using extended idle mode DRX and the MS is expected to respond to paging before the time indicated by the SMS-GMSC, the MSC in Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [45]) or SGSN (or the MME for the SMS in MME feature) may buffer and send the Short Message to the MS until that time.

NOTE 1: Operation 5 is not used by the SGSN.

Figure 15aa): Successful short message transfer attempt via the SMS Router, and the MSC or SGSN

Operation 4a: The SMS-GMSC indicates in the ForwardShortMessage the time until which it waits for receiving the Delivery Report.

Operations 4b to 6: If the MS is using extended idle mode DRX and the MS is expected to respond to paging before the time indicated by the SMS-GMSC, the MSC in Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [45]) or SGSN(or the MME for the SMS in MME feature) may buffer and send the Short Message to the MS until that time.

Figure 15b): Short message transfer attempt failing due to error at the SMS‑GMSC

Figure 15c): Short message transfer attempt failing due to negative outcome of
HLR information retrieval

Figure 15ca) Short message transfer attempt via the SMS Router failing due to negative outcome of HLR information retrieval

NOTE: If an SMS Router is present, the message flow in 15aa is used, except that a 4c Failure Report message is transparently transferred to the SMS‑GMSC from the MSC or SGSN by the SMS Router instead of a 4b Delivery Report.

Figure 15d): Short message transfer attempt failing due to error at the MSC or SGSN

Figure 15e): Short message transfer attempt failing due to negative outcome of
VLR information retrieval

NOTE 1: This operation is not used by the SGSN.

NOTE 2: If an SMS Router is present, the message flow in 15aa is used, except that a 4c Failure Report message is transparently transferred to the SMS‑GMSC from the MSC or SGSN by the SMS Router instead of a 4b Delivery Report.

Figure 15f): Short message transfer attempt failing due to erroneous message transfer
on the radio path

NOTE 1: This operation is not used by the SGSN.

NOTE 2: Two addresses (SGSN and MSC) are received from HLR.

NOTE 3: Both successful transfer over second path and unsuccessful transfer over first path (e.g. Absent subscriber) are sent to HLR.

NOTE 4: The SMS transfer towards the second path is only triggered by the reception of some MAP errors on the first path as described in clause 8.1.1.

Figure 15g): Short message transfer attempt failing over the first path (e.g. SGSN) and
succeeding over the second path (e.g. MSC)

NOTE 1: Operation 5 is not used by the SGSN.

NOTE 2: In Operation 2b, two addresses are received from the SMS Router by the SMS‑GMSC. Both contain the address of the SMS Router, however, each address identifies delivery to the MS via the MSC or via the SGSN.

NOTE 3: In Operation 3, both successful transfer over second path and unsuccessful transfer over first path (e.g. Absent subscriber) are sent to the HLR.

NOTE 4: The SMS transfer towards the second path is only triggered by the reception of some MAP errors on the first path as described in clause 8.1.1.

Figure 15ga): Short message transfer attempt via the SMS Router failing over the first path (e.g. SGSN) and succeeding over the second path (e.g. MSC)

NOTE 1: This operation is not used by the SGSN.

NOTE 2: Two addresses (SGSN and MSC) are received from HLR.

NOTE 3: Unsuccessful transfer over the second path (e.g. MemoryCapacityExceeded) and over the first path (e.g. Absent subscriber) are sent to HLR.

NOTE 4: The SMS transfer towards the second path is only triggered by the reception of some MAP errors on the first path as described in clause 8.1.1.

NOTE 5: If an SMS Router is present, the message flow in 15ga is used, except that a 4c Failure Report message is transparently transferred to the SMS‑GMSC from the MSC or SGSN by the SMS Router instead of a 4b Delivery Report.

Figure 15h): Short message transfer attempt failing over the first path (e.g. SGSN) and
over the second path (e.g. MSC)

Operation 1: Message transfer SC ‑> SMS‑GMSC.

This operation is used to transfer a short message from an SC to an SMS‑GMSC.

The operation consists of:

‑ the transfer of a message containing the TPDU from the SC to the SMS‑GMSC (see "1a. Message transfer" in figure 15); and

‑ the return of either a "Failure report" (see 1c. in figure 15) or a "Delivery report" (see 1b. in figure 15).

"Failure report" is returned to the SC when the SMS‑GMSC has received indication from another entity (MSC, SGSN or HLR) the procedure was unsuccessful. The error indications which the SMS‑GMSC may receive from the MSC, SGSN, HLR, VLR or MS enable the SMS‑GMSC to return one of the error indications given in clause 3.3 back to the SC.

Operation 2: sendRoutingInfoForShortMsg.

The operation is an interrogation of the HLR by the SMS‑GMSC or the SMS Router to retrieve information necessary to deliver the short message.

The result may contain the MSC, SGSN, both MSC and SGSN addresses, or the address of the SMS Router. It shall also indicate which address belongs to the MSC and the SGSN, however, it shall not indicate if the address belongs to an SMS Router (as the SMS Router poses as either an MSC or an SGSN or both to the SMS-GMSC).

Operation 3: SM-DeliveryReportStatus.

The operation provides a means for the SMS‑GMSC to request the HLR to add an SC address to the MWD, and is activated when the SMS‑GMSC receives an absent subscriber indication from the MSC, SGSN or both, and/or when the SMS‑GMSC receives a failure report for a short message transfer with cause MS Memory Capacity Exceeded via the MSC or SGSN. The Return Result optionally contains the MSIsdn‑Alert or IMSI-Alert.

This operation is also activated at successful delivery short message when the MNRF, MNRG or both are set in HLR.

The operation consists of:

‑ the transfer of a message, containing the MSISDN or IMSI of the MS to which the short message was addressed, the SC‑address, the successful outcome and/or the causes (Absent Subscriber, MS memory capacity exceeded or both) for updating the MWD, from the SMS‑GMSC to the HLR (see 3. in figure 15).

Operation 4: forwardShortMessage.

The operation provides a means for the SMS‑GMSC to transfer a short message to the MSC or to the SGSN at which the MS is currently located, via an SMS Router if deployed by the HPLMN of the receiving MS.

The operation works in tandem with the forwarding of the short message from the MSC or from the SGSN to the MS. Thus, the outcome of the operation comprises either success, i.e. that the message has been delivered to the MS; or a failure that may be caused by several reasons, e.g. failure in the transfer SMS‑GMSC ‑> MSC or SMS-GMSC -> SGSN, MS being detached, MS being temporarily unreachable (e.g. due to eDRX), or no paging response.

It should be noted that the MNRG setting is implicitly carried out in the SGSN when the message transfer is denied due to GPRS DETACH.

Operation 5: sendInfoForMT‑SMS.

The operation provides a means for the MSC to retrieve subscriber information from VLR for mobile terminated short message transfer. The operation may be associated with an authentication procedure, as shown in figure 16. Unsuccessful retrieval (e.g. absent subscriber) is indicated by a cause indication to the SMS‑GMSC.

An overall depiction of how operation 5 interacts with signalling on the radio path is given in figure 16.

It should be noted that the MNRF setting is implicitly carried out when the message transfer is denied due to IMSI DETACH.

NOTE: This operation is not used by the SGSN.

Operation 6: Message transfer MSC ‑> MS.

The operation is used to transfer a short message from the MSC to the MS.

If the transfer is not successful, e.g. due to the MS losing radio coverage after having successfully authenticated, a failure report (RP‑ERROR) is returned to the SMS‑GMSC. In this case, MWD and MCEF in the HLR shall be updated only for the case where the transfer fails with cause MS Memory Capacity Exceeded.

If the MS notifies the network that the MS has been unable to accept a short message because its memory capacity has been exceeded, then the ME shall set the memory capacity Exceeded Notification flag if present.

Operation 7: InformSC.

The operation is used to transfer the MSIsdn‑Alert or IMSI-Alert from the HLR to the SMS‑GMSC if the error Absent Subscriber or a positive result is given as an answer to the operation SendRoutingInfoForSM.

	: Operation invocation or message transfer
	: Successful operation invocation or message transfer incl. report

NOTE 1: Described in 3GPP TS 24.008 [12] and 3GPP TS 29.002 [15].

If the SGSN is used, Paging and Authentication are performed from SGSN.

NOTE 2: This operation is not used by the SGSN.

NOTE 3: If an SMS Router is present, the message 4a forwardShortMessage and 4b Delivery report are transparently transferred from/to the SMS‑GMSC to/from the MSC or SGSN by the SMS Router.

Figure 16a): "Send information for MT SMS" procedure; error free case

	: Operation invocation or message transfer
	: Error report

NOTE 1: The GPRS DETACH information is in the SGSN.

This operation is not used by the SGSN.

NOTE 2: If an SMS Router is present, the message 4a forwardShortMessage and 4c Failure report are transparently transferred from/to the SMS‑GMSC to/from the MSC or SGSN by the SMS Router.

Figure 16b): "Send information for MT SMS" procedure;
erroneous case: absent subscriber (e.g. IMSI DETACH or GPRS DETACH)

	: Operation invocation or message transfer
	: Error report

NOTE 1: Described in 3GPP TS 24.008 [12] and 3GPP TS 29.002 [15].

If the SGSN is used, Paging is performed from SGSN.

NOTE 2: This operation is not used by the SGSN.

NOTE 3: If an SMS Router is present, the message 4a forwardShortMessage and 4c Failure report are transparently transferred from/to the SMS‑GMSC to/from the MSC or SGSN by the SMS Router.

Figure 16c): "Send information for MT SMS" procedure;
erroneous case: Absent subscriber (e.g. no paging response)

: Operation invocation or message transfer

: Error report

: Unsuccessful operation invocation or message transfer including error report

(or with missing confirmation)

NOTE 1: Described in 3GPP TS 24.008 [12] and 3GPP TS 29.002 [15].

If the SGSN is used, Paging and Authentication are performed from SGSN.

NOTE 2: This operation is not used by the SGSN.

NOTE 3: If an SMS Router is present, the message 4a forwardShortMessage and 4c Failure report are transparently transferred from/to the SMS‑GMSC to/from the MSC or SGSN by the SMS Router.

Figure 16d): "Send information for MT SMS" procedure; incorrect authentication

NOTE 1): This operation is not used by the SGSN or MME.

Figure 17a): Successful short message transfer attempt via the MSC, SGSN or MME, with short message retransmission by the SMS-GMSC at the time requested by the MSC, SGSN or MME

Operation 4a: the SMS-GMSC indicates in the ForwardShortMsg that it is capable to retransmit the Short Message until a maximum retransmission time.

Operation 4c: If the MS is using extended idle mode DRX, and if the ForwardShortMsg includes a maximum retransmission time, the MSC in Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [45]), SGSN or MME may return a Delivery Report with a cause indicating that the user is temporarily unreachable and with an indication requesting the SMS-GMSC to retransmit the Short Message at a later requested retransmission time prior to the maximum retransmission time. In that case, the MSC in Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [45]), SGSN or MME shall not set the MNRF, MNRG or MNRF flag respectively. The SMS-GMSC shall not send an SM-Delivery Report Status to the HLR or HSS.

Operation 5a: the SMS-GMSC retransmits the Short Message at the requested retransmission time.

NOTE: This procedure does not cause additional signalling to the HSS to retransmit the Short Message.

NOTE 1): This operation is not used by the SGSN or MME.

Figure 17b: Successful short message transfer attempt via the MSC, SGSN or MME, with short message retransmission by the SMS-GMSC upon MS originated signalling prior to the retransmission time requested by the MSC, SGSN or MME

Operation 4a: same as for Figure 17a).

Operation 4c: same as for Figure 17a).

Operation 5b: Upon MS originated signalling to the same MSC in Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [45]), SGSN or MME, the MSC in Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [45]), SGSN or MME sends an Alert Service Center to the SMS-GMSC to trigger the immediate retransmission of the Short Message.

Operation 6a: the SMS-GMSC retransmits the Short Message immediately.

Figure 17c): Successful short message transfer attempt via the MSC, SGSN or MME, with short message retransmission by the SMS-GMSC upon MS mobility to a new serving node prior to the retransmission time requested by the MSC, SGSN or MME.

Operation 4a: same as for Figure 17a).

Operation 4c: same as for Figure 17a).

Operation 5c: Upon MS mobility to a new SGSN or MME prior to the retransmission time requested by the old SGSN or MME, the old SGSN or MME signals to the new SGSN or MME (in the Context Response during a RAU or TAU procedure or in the Forward Relocation Request during a Handover procedure), that there is a pending MT Short Message to be sent to the MS.

Operation 5d: if so, the new SGSN or MME signals its MAP or Diameter address for MT SMS to the old SGSN or MME (in the Context Acknowledge during a RAU or TAU procedure or in the Forward Relocation Response during a Handover procedure). The new SGSN or MME also maintains the signalling connection with the MS for a longer time to enable the retransmission of the Short Message.

Operation 5e: Based on Deployment Option 2 (see clause 8.2.4a.1 of 3GPP TS 23.272 [45]), upon receipt of a Cancel Location Request the old MSC sends an Alert Service Center message to the SMS-GMSC with an indication that the MS has moved to another serving node, to trigger the immediate retransmission of the Short Message towards the new serving node. Upon mobility to a new MME without MSC change (for SMS over SGs), the MSC sends an Alert Service Center message to the SMS-GMSC with an indication that the MS is available for MT SMS to trigger the immediate retransmission of the Short Message to the MSC.

Upon receipt of a Cancel Location Request, Context Acknowledge or Forward Relocation Response, the old SGSN or MME sends an Alert Service Center message to the SMS-GMSC, with an indication that the MS has moved to another serving node, and with the new serving node’s address if received at step 5d, to trigger the immediate retransmission of the Short Message towards the new serving node.

Operation 6a: If the Alert Service Center message indicates that that the MS has moved to another serving node but the message does not contain the new serving node’s address, the SMS-GMSC retrieves the new serving node’s address from the HLR or HSS.

Operation 6c: the SMS-GMSC retransmits the Short Message immediately towards the new serving node.