With HD (High Definition) telephony, you will experience natural sound quality during calls. When using HD technology to make a call, the full frequency spectrum of speech is transmitted, resulting in realistic voice reproduction. To conduct calls in HD quality, a number of requirements must be met:

• The telephone call must be made entirely over the internet or an ISDN connection. HD telephony can also be used for internal calls. HD telephony cannot be used if the telephone is connected to an analog extension on the FRITZ!Box or if one of the parties is conducting the call over an analog line.
• All telephones, the telephone systems, and the telephony provider must support the speech codec G.722. Cordless telephones must also support HD telephony.

  Note:All current FRITZ!Fon models support HD telephony and G.722. To find out whether telephones from another manufacturer support HD telephony and G.722, refer to the manufacturer.