Content for TS 23.540 Word version: 18.3.0
1…
4…
5…
5.1.3
5.1.4
5.1.5
5.1.6
5.1.7…
5.1.7.2.3…
5.1.7.3.2
5.1.7.3.3
5.1.7.3.4
5.1.7.3.5
5.1.7.4
5.1.8…
5.2…
6…
5.1.3 Successful Mobile Terminated short message transfer via SMS Router p. 14
Step 1.
MT SMS interaction between SC and SMS-GMSC follow the current procedure as defined in TS 23.040.
step 2a. SMS-GMSC invokes the Nnrf_NFDiscovery to discover and select the UDM instance(s), supporting SMS SBI interfaces, and managing the user subscriptions of the GPSI. The SMS-GMSC may need to retrieve the PLMN ID of the recipients GPSI before the discovery of the UDM instance based on the GPSI-to-Subscription-Network resolution procedure defined in clause 5.1.7.
step 2b. If no UDM supporting SMS SBI could be discovered, the NRF indicates so to SMS-GMSC (by not including any UDM instance in the discovery response), and SMS-GMSC shall quit the SBI-based procedure and fallback to legacy (MAP/Diameter) protocol based procedures, as defined in TS 23.040,
or if a UDM supporting SMS SBI is discovered and selected, NRF returns the IP addresses or FQDNs of the serving UDM to provide Nudm_UECM_SendRoutingInfoForSM service to SMS-GMSC.
Step 3.
SMS-GMSC invokes Nudm_UECM_SendRoutingInfoForSM (GPSI) to the UDM to get the serving node information for all access types for the UE.
Step 4.
The UDM shall check the registration/reachability flags to determine the potential target nodes, e.g. SMSF. For MT SM transfer via SMS Router, the UDM shall invoke the Nrouter_SMService_RoutingInfo to provide the SMSF Instance Id to the SMS Router. The address of the SMS Router to be contacted by the UDM may be configured locally.
Step 5.
The SMS Router shall send Nrouter_SMService_RoutingInfo response to the UDM.
Step 6.
UDM responds to the SMS-GMSC by sending Nudm_UECM_SendRoutingInfoForSM response, including SMS Router address, the indication for SMSF SMS_SBI support and the indication for SMS Router SMS_SBI support.
Step 7-8.
The SMS-GMSC forwards the SMS message to the SMS Router, and then SMS Router forwards the SMS message to the SMSF. If the SMS Router has more than one SMSF address to use for SMS transport towards the UE, then the SMS Router chooses which SMSF address to use first, based on operator local policy.
The SMS-GMSC selects protocol based on the indications for SMSF SMS_SBI support and SMS Router SMS_SBI support.
If both SMSF and SMS Router indicate support for SMS_SBI, SMS-GMSC discovers the appropriate service instance(s) of the target SMS Router and forwards the SMS message to the SMS Router by invoking Nrouter_SMService_MtForwardSm service operation. And then the SMS Router forwards the SMS message to the SMSF by invoking Nsmsf_SMService_MtForwardSm service operation.
If SMSF or SMS Router indicates that it does not support SMS_SBI, SMS-GMSC should forward SMS message to SMS Router by legacy MAP/Diameter protocol. Then SMS Router forwards the SMS message to the SMSF by legacy MAP/Diameter protocol. The following steps follow the procedures for legacy MT SMS message transfer, as illustrated in Figure 15aa of TS 23.040.
Step 9.
MT SMS over NAS procedure between SMSF, AMF and UE is same as the definition in step 4a to 6b of Figure 4.13.3.6-1 in TS 23.502.
Step 10.
The SMSF delivers the delivery report to SMS Router by sending the Nsmsf_SMService_MtForwardSm response to the SMS Router.
Step 11.
The SMS Router delivers the delivery report to SMS-GMSC by sending the Nrouter_SMService_MtForwardSm response to the SMS-GMSC.
Step 12-13.
The SMS-GMSC may report the SM-Delivery Status to the UDM by invoking Nudm_ReportSMDeliveryStatus_Request and UDM responses Nudm_ReportSMDeliveryStatus_Request response to SMS-GMSC.
Step 14.
The SMS-GMSC delivers the delivery report to SC as defined in TS 23.040.
Step 15.
MT SMS over NAS procedure between SMSF, AMF and UE is same as the definition in step 6c to 6d of Figure 4.13.3.6-1 in TS 23.502.
