6.14 Service-level interworking: IM or CPM user receives Short Message from an SMS user

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 [2], 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.