high definition telephony

In principle, the voice quality oftelephony has not changed since the 1930s. At that time, the frequency range for telephony was set from 300 Hz to 3.4 kHz. This still applies today. And digitization has not changed this. It doesn't matter whether you make a call via ISDN or a mobile network. The voice quality remains poor.

Decisive for the voice quality of ISDN are the voice codecs according to G.711, which transmit audio with 3.5 kHz, although there is a qualitatively better voice codec with G.722, which was not built into telephones or PBXs in the past. But now, in the course of Internet telephony( VoIP) is used. In today's digital networks, the codecs are in the exchanges. With the change to the Next Generation Networks( NGN) and with VoIP, there would definitely be approaches to improve the voice quality towards HD telephony. These networks are much more flexible and the end stations can negotiate their protocols among themselves.

Inmobile communications, HD Voice and Full HD Voice are two voice services with high fidelity, speech intelligibility and playback quality. The two services, which use special voice compression, have a sound quality that corresponds to an adequate bandwidth of 7 kHz (HD Voice) and 20 kHz (Full HD Voice).