9 Protocols and protocol architecture

23.0403GPPRelease 17Technical realization of the Short Message Service (SMS)TS

The protocol layers of the SMS are structured as shown in figure 7.

NOTE: The SMS Router is an optional functional entity, and is used only in the MT case.

Figure 7: Protocol layer overview for the Short Message Service

The present document specifies the protocol at the SM‑TL, the service offered by the SM‑TL at the MS and the SC, and the service offered by the SM‑RL at the SC.

Note that while normally SM-TL terminates at the SC in SM MO, the SMS-IWMSC may inspect TP-DA in SMS-SUBMIT for the purpose of checking the existence of an SMS interworking agreement (see clause 8.2.2).