All FRITZ!Fon models support the DECT standard and the DECT-GAP profile. The DECT GAP profile makes it possible to use cordless telephones with base stations from other manufacturers and covers basic functions such as registering telephones with base stations and establishing telephone calls.

However, DECT GAP does not define additional convenience functions, which means that we cannot guarantee they will work with a base station from a different manufacturer. The call list, telephone book, answering machine, clock, internet services, software update function, RSS feeds, and email are only available if a FRITZ!Box is used as the base station.

By default, German is the default language of FRITZ!Fon. After it registers with a FRITZ!Box, it uses the language set in the FRITZ!Box user interface. Since the language selection is controlled automatically, you cannot change the language if the telephone is registered with a base station from a different manufacturer.