Security arrangement and method in a data communication system

The present invention relates to an arrangement and method for providing wireless data communication services, between a client station (10) and a service providing station (15) and/or a computer network (13, 33), each of the client station (12), service providing station (15) or the computer network (13, 33) being connected to at least one radio transceiver (11, 12) and each being arranged with means (20, 30, 31) to convert data to be transmitted to data packets or data packets to data. The radio transceiver (11, 12) is arranged to transmit and/or receive data packets with at least one predetermined, by a user determined or randomly selected low radio frequency, said low radio frequency being within a range of about 1 kHz to about 30 MHz, preferably one or several of: 100-1800 kHz, 1810-1850 kHz, 3500-3800 kHz, 7000-7100 kHz, 10100-10150 kHz, 14000-14350 kHz, 18068-18168 kHz, 21000-21450 kHz, 24890-24990 kHz and 28000-29700 kHz bands.