Comfort Noise Generation, comfort noise (CNG), is a technique that generates noise and is used in digitalvoice communications.
Noise generation is used in digital telephony because with digital technology, one does not hear background noise during voice pauses and might assume that the line is disconnected. For this reason, pink noise is inserted as a light background noise in voice pauses. This was different with analog phone calls, where background noise could always be heard, albeit often an unwanted one.
Various voice codecs used in digital voice networks and Internet telephony have mastered the comfort noise technique.