17.1. Overview

The General Packet Radio Service (GPRS) is the Packet-Switched (PS) domain of the Global System for Mobile communications (GSM) and the Universal Mobile Telecommunications System (UMTS) network. It provides Internet Protocol (IP) connectivity to attached User Equipment (UE) via so-called Packet Data Protocol (PDP) contexts. As expressed in the name, it is a logical connection (context) that is related to a specific packet-based protocol.

The UE will be able to send IP packets over the air interface after it has established a PDP context.

This chapter concentrates only on those parts of GPRS that are necessary for a UE to access an IP Multimedia Subsystem (IMS) network. The detailed procedures within the Gateway GPRS Support Node (GGSN) or the Serving GPRS Support Node (SGSN), as well as detailed message coding and flows are not discussed here. The aim of this chapter is to provide the reader with a short overview of the basic principles that lie behind GPRS and its PDP contexts.

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