Besides cellular mobile radio networks that are primarily envisaged for use outdoors, systems that have been specifically designed for use in buildings are also important. In recent years cordless telephones with a range of a few hundred metres have become increasingly popular in private households. There is (along with CT2/CAI) a digital alternative to these analogue devices that offers better voice quality and a greater security against eavesdropping, as well as other advantages: the DECT system