Abstract: Comfort noise functions monitor background noise picked up by microphones in radiocommunication systems. These functions provide comfort noise information which is transmitted by remote units during periods of silence, so that the receiving party's equipment can output the proper background noise while the transmitting side can deactivate the transmitting circuitry to conserve power. Muting functions are accommodated by continuing to provide signals to the comfort noise functions so that the background noise is continuously monitored. When the muting mode of a remote unit is enabled, the transmitter receives comfort noise frames or silence frames instead of information output from a voice (speech) encoder.