Digital call quality

The term digital call quality had entered into popular English language in the late 20th century at a time of increasing popularity of GSM mobile (cell) phones ('2G') replacing the preceding analogue system. The popular meaning of the phrase is taken to suggest GSM audio performance is comparable to that of digital audio (such as Philips Audio Compact Disc)^{[citation needed]}. However, the difference here is the GSM system has been optimised to use only the minimum bandwidth required to make the caller's voice recognisable to the callee, and to recreate most of the sounds that spoken words use, sufficiently for spoken sentences to be understandable.

Generally digital call quality (GSM encoding) sometimes fails to communicate certain tonal information within the voice used in human communication beyond the spoken word^{[citation needed]}. (This is present in an analog channel). These include the physiologically-influenced modifications of the human voice due to the act of lying and other emotional effects affecting such things as rapid pitch delta of the voice^{[citation needed]}. There are also some spoken languages and dialects which are affected more by GSM encoding than others, especially where such tongues rely on the communication of information that GSM encoding can miss^{[citation needed]}. Additionally, because the duplex audio link each contains a significant time delay each direction, means conversations are not 'live'^{[citation needed]}.

(Note that although the previous analogue mobile phone system utilised a wider bandwidth, it operated on the simpler principle of faithfully conveying analogous 'voice-shaped' signals in real time between the calling parties, permitting additional audible communication to take place between individuals by using other than just the spoken word and missed by digital call quality).