Having described the internal operation of UMTS in Chapter 4, we can go on to consider how the system provides services to the user. We begin by explaining how services are classified and how the network provides the user with the quality of service required. We then give a detailed description of the two most important services that UMTS provides: voice and the general packet radio service (GPRS). We focus on the signalling messages that set up, manage and tear down voice calls and data transfers, and also on the mechanisms that are used to transfer information between the mobile and the end device.

The second half of the chapter is a shorter account of the other services provided by UMTS. This account is in two parts. The first part covers the other services that are of interest to the user, such as the short message service (SMS) and the multimedia messaging service (MMS). The second part covers the toolkits that application developers can use to build up higher level services. The chapter closes with an overview of the procedures that are used for charging and billing.

Service classification

Ultimately, the purpose of UMTS is to provide services that the end user will pay for. The services defined by the 3GPP specifications fall into four categories.

User services define both the data transport mechanism and the application software, so they provide a complete end-to-end service for the user.