7.5.4 Handling of mobile terminating SMS
23.0783GPPCustomised Applications for Mobile network Enhanced Logic (CAMEL) Phase 4Release 17Stage 2TS
7.5.4.1 Handling of mobile terminating SMS in the terminating MSC or SGSN
A CAMEL Service may be invoked for the following Mobile Terminated short message types:
– Short Message Delivery (TPDU type = SMS-DELIVER)
– Short Message Status Report (TPDU type = SMS-STATUS-REPORT)
Refer to 3GPP TS 23.040 [14] for a description of the various TPDU types and to 3GPP TS 24.011 [31] for a description of the protocol elements of the Short Message Relay Layer (RPDUs).
The functional behaviour of the terminating MSC or SGSN is specified in 3GPP TS 29.002 [34]. The procedures specific to CAMEL are specified in the following subclauses:
7.5.4.1.1 Procedure CAMEL_T_SMS_INIT;
This procedure is called when a Short Message delivery attempt is received from the SMS-GMSC. If MT‑SMS‑CSI is present for the subscriber, then the SMS_SSF shall be invoked. Otherwise, the Short Message delivery attempt proceeds without CAMEL.
When the SMS_SSF is invoked and the SMS_SSF has requested the gsmSCF for instructions, the MSC or SGSN may receive the following responses from the SMS_SSF:
– Int_Continue_SMS
The gsmSCF has indicated that SM delivery may proceed. It may have supplied the SMS_SSF with a modified Calling Party Number. This Calling Party Number shall replace the TP-Originating-Address in the SMS-DELIVER TPDU.
– Int_Release_SMS
The gsmSCF has force-released SM delivery. The RP Cause received from the gsmSCF shall be conveyed to the SMS-GMSC in the RP-Cause component, in the RP-ERROR RPDU.
– Int_Error
A Tssf time-out or an internal SMS_SSF error has occurred; the SM has not been forwarded to the Mobile Station. If Default SMS Handling equals ‘Continue’, the SM delivery proceeds. Otherwise, SM delivery shall be aborted. In the latter case, the RP-Cause component, in the RP-ERROR RPDU shall be set to EquipmentProtocolError, in accordance with 3GPP TS 29.002 [34].
7.5.4.1.2 Procedure CAMEL_T_SMS_DELIVERED
This procedure is called when the MSC or SGSN has detected that delivery of the SM to the Mobile Station has succeeded. No event specific information is sent to the gsmSCF.
When Short Message delivery attempt success has been reported to the gsmSCF, then the MSC or SGSN may receive the following responses from the SMS_SSF:
– Int_Continue_SMS
The event was reported to the gsmSCF in interrupt mode. The gsmSCF has concluded CAMEL processing and has terminated the Service Logic.
– Int_Continue
The event was not reported to the gsmSCF or was reported in notification mode.
– Int_Error
A Tssf time-out has occurred.
In all the above cases, the SM processing in the MSC or SGSN continues.
7.5.4.1.3 Procedure CAMEL_T_SMS_FAILURE
This procedure is called when the MSC or SGSN has detected that delivery of the SM to the Mobile Station has failed. If the delivery failure is due to RP-ERROR RPDU received from the MS, then the MT SMS Cause in the event report to the gsmSCF shall be set to the RP-Cause component in the RP-ERROR-RPDU. Otherwise, if the delivery failure is due to internal failure in the MSC or SGSN, CP-ERROR from MS or time-out from the MS, then the MT SMS Cause in the event report to the gsmSCF shall be set to "Protocol error, unspecified", as defined in 3GPP TS 24.011 [31].
When Short Message delivery attempt failure has been reported to the gsmSCF, then the MSC or SGSN may receive the following responses from the SMS_SSF:
– Int_Continue_SMS
The event was reported to the gsmSCF in interrupt mode. The gsmSCF has concluded CAMEL processing and has terminated the Service Logic.
– Int_Continue
The event was not reported to the gsmSCF or was reported in notification mode.
– Int_Error
A Tssf time-out has occurred.
In all the above cases, the SM processing in the MSC or SGSN continues.
7.5.4.1.4 Allocation of SMS Reference Number
During the CAMEL handling of a Mobile Terminating Short Message, the MSC or SGSN shall allocate an SMS Reference Number. This SMS Reference Number shall be placed in the SMS-MT Call Detail Record, together with the MSC Address or SGSN Number. This SMS Reference Number shall also be sent to the gsmSCF in the Initial DP SMS Information Flow, together with the MSC Address or SGSN Number. The combination of SMS Reference Number and MSC Address or SGSN Number forms a globally unique pair. This pair may be used for correlation of CDRs produced in the MSC or SGSN with CDRs produced in the gsmSCF.
An SMS Reference Number shall be generated and placed in the SMS-MT Call Detail Record, for every Short Message, including the case when a Short Message forms part of a set of concatenated Short Messages.
Figure 7.10-1: Procedure CAMEL_T_SMS_INIT (sheet 1)
Figure 7.10-2: Procedure CAMEL_T_SMS_INIT (sheet 2)
Figure 7.11-1: Procedure CAMEL_T_SMS_FAILURE (sheet 1)
Figure 7.12-1: Procedure CAMEL_T_SMS_DELIVERED (sheet 1)
7.5.4.2 Handling of mobile terminating SMS in the VLR
The functional behaviour of the VLR is specified in 3GPP TS 29.002 [34]. The handling specific to CAMEL is specified in the following procedure:
– Procedure CAMEL_MT_SMS_VLR.
Figure 7.13-1: Procedure CAMEL_MT_SMS_VLR (sheet 1)
7.5.4.3 CAMEL subscription check for mobile terminating SMS in the SGSN
The functional behaviour of the SGSN for delivery of MT shrt message is specified in 3GPP TS 29.002 [34]. The procedure for checking CAMEL capability and subscription information is specified in the following procedure:
– Procedure CAMEL_MT_SMS_SGSN.
Figure 7.14-1: Procedure CAMEL_MT_SMS_SGSN (sheet 1)