General packet radio service (GPRS) is a packet-based data transmission service for the GSM network. GPRS splits the data into separate packets and adds additional information to enable the network to identify the intended receiver and reassemble the information from the separate packets.

The service is based on the internet protocol (IP) which is also used in the internet and which enables data transmission without a direct dial-up to the receiver. This means that during the data transmission a line is not exclusively reserved for the sender and receiver. Using different routes, the GPRS system is able to direct the individual packets from the sender to the receiver. This guarantees excellent use of the available capacity. The receiver then places the individual data packets in the right order and reassembles the original bit sequence.

Multiple users share 1 transmission channel
A GSM mobile phone channel is divided into 8 time slots. In the case of conventional GSM data transmission the user occupies 1 time slot for the complete duration of the connection. First disadvantage: If all the time slots are in use, no further person can access the network. Second disadvantage: The user has to pay for the whole period of time used by conventional GSM transmission regardless of the amount of data transmitted and regardless of whether data was continuously transmitted or whether there were longer breaks in the transmission of the data.

GPRS, on the other hand, makes the time slots simultaneously available to multiple users and the channel is not exclusively reserved for a single connection. This means the time slot remains in use when there is a break in the transmission as the slot is made available to other users. This procedure uses the capacity of the network more efficiently. Furthermore, this packet-based system is very cost-effective as invoicing is made according to the volume of data transmitted and not according to the duration of the connection time.

High speed
In addition to the changed invoicing practice users also benefit especially from higher data transmission rates of GPRS compared to standard GSM. The network can make a number of time slots available for data transmission. One common configuration uses 3 or 4 time slots for the receipt of data and 1 or 2 time slots for the sending. A download via 4 time slots will therefore result in a transmission data rate of up to 53.6 kbit/s.

In practice a number of different factors influence the bandwidth of the GPRS network. The actual maximum possible speed in one cell depends on the volume of data transmitted, the configuration of the mobile telephone, the network itself, and from the volume of general telephone conversations taking place within the mobile phone cell.