The SMS-GMSC indicates in the ForwardShortMessage the time until which it waits for receiving the Delivery Report.
Operations 4b to 6:
If the MS is using extended idle mode DRX and the MS is expected to respond to paging before the time indicated by the SMS-GMSC, the MSC in Deployment Option 2 (see clause 8.2.4a.1 of TS 23.272) or SGSN (or the MME for the SMS in MME feature) may buffer and send the Short Message to the MS until that time.
The SMS-GMSC indicates in the ForwardShortMessage the time until which it waits for receiving the Delivery Report.
Operations 4b to 6:
If the MS is using extended idle mode DRX and the MS is expected to respond to paging before the time indicated by the SMS-GMSC, the MSC in Deployment Option 2 (see clause 8.2.4a.1 of TS 23.272) or SGSN(or the MME for the SMS in MME feature) may buffer and send the Short Message to the MS until that time.