The radio modem transmits data several kilometers over a wireless connection to another radio modem over a point-to-point or -multipoint link. Radio modems are independent of mobile and satellite network operators and no cost is thus associated with transferring data. Private radio modem networks can use either unlicensed (e.g. ISM) or licenced frequency bands (UHF, VHF).
The operation range of a radio modem varies depending on the transmission power, antenna gain and mast height, and environment. In rural areas a 1 W radio modem with a line-of-sight radio link may range over 20 km and even up to 50 km in exceptionally amicable environments. In dense metropolitan areas, a corresponding range may vary from several kilometres to over 10 km. With a 10 W radio modem, a range of up to 100 km can be reached in favorable environments. By using radio modem repeaters, much broader areas can be covered.