Whilst GSM (2G) networks are excellent for voice calls, they are limited when it comes to sending and receiving data. GSM phones use a technology called CSD (Circuit Switched Data) to transfer data. CSD requires the phone to make a special connection to the network before it can transfer data (like making a voice call) which can take up to 30 seconds. Once connected, the data is sent or received and the user is billed for the time spent online. Data transfer is relatively slow: 14.4 kbps (kilobits per second) for GSM 1800 networks (Orange and T-Mobile) and 9.6 kbps for GSM 900 networks (Vodafone and O2).

GPRS (General Packet Radio Service) is a method of enhancing 2G phones to enable them to send and receive data more rapidly. With a GPRS connection, the phone is "always on" and can transfer data immediately, and at higher speeds: typically 32 - 48 kbps. An additional benefit is that data can be transferred at the same time as making a voice call. GPRS is now available on most new phones.

GPRS is part of a series of technologies that are designed to move 2G networks closer to the performance of 3G networks. The key characteristic of a 3G network is its ability to transfer large amounts of data at high speed (up to 2 Mbps), enabling applications like video calling, video downloads, web browsing, email, etc. By increasing the speed of a 2G network, some of these applications become possible, e.g. web browsing and sending or receiving emails with large attachments. These technologies are called 2.5G and include enhancements to the CSD technology, such as HSCSD and EDGE.

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