UE uses Short Message Mobile Originated procedure as specified in TS 23.040
to delivery small data to SCS/AS. The service centre address points to the SMS-SC which contain the function described in this procedure, the destination SME address is set to short/long code of the SCS/AS, and Application Port ID element of the TP-User-Data field is set to an the appropriate value.
For MSISDN-less subscription, the MSC/VLR/MME/SGSN/IP-SM-GW uses the dummy MSISDN. This MSISDN and the IMSI of the UE are sent using existing SMS delivery procedure (e.g. MAP MO forward SM operation) to SMS-SC.
SMS-SC indicates to UE that it has successfully received the SMS message using existing SMS Submit Report defined in TS 23.040
SMS-SC uses the destination SME address (long/short code of the SCS/AS) to identify the corresponding MTC-IWF based on a pre-configured mapping table. SMS-SC extracts the SMS payload, Application port ID, and IMSI of the UE and deliver them to MTC-IWF via T4 along with the destination SME address (long/short code of the SCS/AS).
Over S6m, MTC-IWF uses the IMSI of the UE and application port ID to query the HSS/HLR for external ID.
Over Tsp, a MTC-IWF forwards the SMS payload, external ID, and Application Port ID to the SCS/AS. The SCS/AS is identified with the destination SME address (long/short code of the SCS/AS) received from step 3. The payload is delivered directly to the SCS/AS, not processed by MTC-IWF.
Via T4, MTC-IWF returns a success or failure delivery indication to SMS-SC.
SMS-SC indicates success/failure of the delivery of the SMS to the target back to UE using existing SMS Status Report defined in TS 23.040