– a band of frequencies clustered around 2.4 GHz has been designated,
along with a handful of others, as the Industrial, Scientific and Medical radio bands
(ISM). This band allows users to operate with no license requirements.
Manufacturers of wireless communication devices (intercoms) have been using 2.4
GHz band for transmitting and receiving voice communications. In the US, the 2.4
GHz ISM band is 2400 – 2483.5 MHz.