GPRS - General Packet Radio Service

as the name suggests - packet-orientated

GPRS is the bundeling of GSM channels 

theoretically up to eight GSM channels 

channels can be added and removed dynamically, based on priorities

in general european networks allow:

bundling of four channels for the downlink (allows 38.400 kbps, one GSM channel offers 9.600 kbps)

bundling of two channels for the uplink