The Short Message Service (SMS) is a basic service allowing the exchange of short text messages between subscribers. The first short text message is believed to have been transferred in 1992 over signaling channels of a European GSM network. Since this successful trial, SMS usage has been the subject of tremendous growth. The Mobile Data Association1 reported that the total number of chargeable person-to-person text messages sent across the four UK GSM networks in 2003 totaled 20.5 billion.
This chapter, dedicated to SMS, first introduces common use cases for SMS such as consumer, corporate, and operator applications. Components of a typical SMS-enabled GSM architecture are presented along with basic SMS features. The four-layer transport protocol stack of SMS (application, transfer, relay, and link) is presented and the transfer layer of this stack is described in detail. The transfer layer is the component which needs to be mastered by implementers for the development of SMS-based applications. An insight is also given into techniques available for exchanging messages between servers and applications running in the SIM. Interworking between SMS and Email is presented and the manipulation of messages via AT commands is illustrated.
Note that the content of this chapter also represents the basis for the next chapter. Chapter 4 describes two application-level extensions of SMS in the form of the Enhanced Messaging Service (EMS).