The MTC-IWF selects a suitable SMS-SC based on configured information. The MTC-IWF sends a Submit Trigger (External Identifier or MSISDN, IMSI, SCS Identifier, trigger reference number, validity period, priority, serving node ID(s) if available from HSS, SMS Application port ID, trigger payload, Trigger Indication) message to the SMS-SC. The SMS-SC should avoid an initial HSS/HLR interrogation (SRI for SM) when it has already received necessary parameters in the Submit Trigger message from the MTC-IWF. The MTC-IWF forwards the Application Port ID received from SCS as the SMS Application port ID which is used to address the triggering function within the UE. The Trigger Indication is a standardised identifier to allow the UE and the network to distinguish an MT message carrying device triggering information from any other type of messages. The SMS-SC does any necessary segmentation for larger messages.
If the MTC-IWF indicates that "Absent subscriber" was received from HSS, the SMS-SC should not submit the message, but store it directly and send Routing Information for SM to request the HSS to add the SMS-SC address to the Message Waiting List.
The SMS-SC sends a Submit Trigger Confirm message to the MTC-IWF to confirm that the submission of the SMS has been accepted by the SMS-SC.
The MTC-IWF sends a Device Trigger Confirm message to the SCS to confirm that the Device Trigger Request has been accepted for delivery to the UE.
Step 4, 5, 6.
The short message is delivered to the UE (see MT-SMS procedures specified in TS 23.040
). This may involve delivery attempts in MSC or MME, SGSN or over IMS via IP-SM-GW (see MT-SMS without MSISDN procedures specified in TS 23.204
The SMS-delivered trigger payload is processed and handled by the triggering function in the UE. Any information contained within the trigger payload is forwarded to the related or addressed UE-application.
The SMS-SC generates the necessary CDR information and includes the SCS Identifier. The SMS Application port ID which is included in the SM User Data Header and the Trigger Indication are included in the CDRs in order to enable differentiated charging. The SMS-SC stores the trigger payload, without routing information. If the message delivery fails and is attempted to be delivered again, HSS interrogation will be performed.
If the message delivery fails and the validity period of this trigger message is not set to zero, the SMS-SC shall send a SM Message Delivery Status Report to request the HSS to add the SMS-SC address to the Message Waiting list. When the message delivery is later re-attempted, a new HSS interrogation will be performed by the SMS-GMSC using IMSI or MSISDN. HSS interrogations using IMSI shall not be forwarded or relayed to SMS-Router or IP-SM-GWs. HSS may include up to three serving node identities (MSC or MME, SGSN, IP-SM-GW) in the response to SMS-GMSC.
If the message delivery fails and depending on the failure cause either directly or when validity period of the trigger message expires, or when the message delivery succeeds, the SMS-SC shall send a Message Delivery Report (cause code, trigger reference number, SCS Identifier) to the MTC-IWF.