THE USE of wireless devices is heavily regulated throughout the world. Each country has a government department responsible for deciding where and how wireless devices can be used, and in what parts of the radio spectrum. Most countries (but not all) have allocated parts of the spectrum for open use, or license-free use. Other parts of the spectrum can only be used with permission or license for each individual application.
Most wireless products for short-range industrial and commercial applications use the license-free areas of the spectrum, to avoid the delay, cost and hassle of obtaining licenses. The license-free bands are also knows as ISM bands -- Industrial, Scientific & Medical..In many countries there are several ISM bands available, in different parts of the spectrum.