FRITZ!Box 4020 Service - Knowledge Base
Prerequisites for HD telephony
HD (High Definition) telephony offers new, natural sound quality when conducting calls. When using HD technology to make a call, the full frequency spectrum of speech is transmitted, resulting in realistic voice reproduction. In order to conduct calls in HD quality, the following prerequisites must be met:
- Both parties must either use Internet telephony (VoIP) or an ISDN line to conduct the call. HD telephony can also be used when conducting internal calls. HD telephony cannot be used if one of the parties is using an analog landline.
- All telephones, PBXs and the telephony provider used for the call must support the speech codec G.722.