A method is provided for allocating a radio resource in a packet switched data transmission system, such as GPRS (General Packet Radio Service), which data transmission system includes terminals and a network. In the method, terminals communicate with the network over the radio interface using the packet transfer mode, and for communication, a radio resource is allocated to the terminal. For allocating the radio resource, for the packet switched implementation of a realtime service, a first message is transmitted from the terminal to the network and the first message is received in the network. The network identifies the first message as a radio resource request for the packet switched implementation of a realtime service and allocates to the terminal the requested radio resource for the packet switched implementation of the realtime service. A wireless terminal and network element relating to the method are also provided.