23.2043GPPRelease 17Stage 2Support of Short Message Service (SMS) over generic 3GPP Internet Protocol (IP) accessTS
An IMS registered user with SIMPLE IM or CPM service receives a Short Message formatted via service-level interworking to an Instant Message.
Figure 6.14: Successful IM termination after service-level interworking
1) The UE registers to the S-CSCF according to the IMS registration procedure.
2) The SMS-SC forwards a Short Message to the SMS-GMSC.
3a) The SMS GMSC interrogates the HSS to retrieve routeing information. Based on the pre-configured IP-SM-GW address for the user, the HSS forwards the request to the corresponding IP-SM-GW.
3b) The HLR/HSS returns the IMSI and the address(es) of the current MSC, SGSN, MME and/or SMSF to the IP-SM-GW for delivery of the SM in CS/PS domain.
3c) The IP-SM-GW creates a MT Correlation ID as per TS 23.040 , which associates the Routing Info retrieval with the subsequent Forward Short Message messages(s), and stores this along with the IMSI of the receiving subscriber. The IP-SM-GW returns to the SMS-GMSC the address of itself, along with the MT Correlation ID in the IMSI field, as routeing information.
4) The SMS-GMSC delivers the Short Message to the IP-SM-GW in the same manner that it delivers the Short Message to an MSC, SGSN, MME or SMSF, including the MT Correlation ID received from the IP-SM-GW, in place of the IMSI.
5) The IP-SM-GW checks whether the recipient is authorized for the interworking service.
NOTE 1: The IP-SM-GW will determine whether the transport-level interworking or the service-level interworking is to be performed according to clause 6.8.3.
6) If the user is authorized for service-level interworking, the IP-SM-GW converts the Short Message to an Instant Message. It sends the Instant Message using the appropriate SIP method towards the S-CSCF.
7) The S-CSCF forwards the Instant Message to the UE.
8) The UE acknowledges the SIP request to the S-CSCF.
9) The S-CSCF forwards the acknowledgement of the SIP request to the IP-SM-GW.
10) The IP-SM-GW acknowledges the Forward Short Message to the SMS-GMSC.
11) The SMS-GMSC sends a Delivery report (SMS‑DELIVER‑REPORT) to the SMS‑SC.
12) The IP‑SM‑GW may send a Report SM Delivery Status to the HLR/HSS.
13) The SMS-GMSC may send a Report SM Delivery Status to the HSS. The HSS shall ignore the information provided in this report.