The MPEG-4 CELP speech codec is standardized as ISO/IEC 14496-3 (MPEG-4 version 1) Audio Part, and its error robustness and silence compression functions are expanded by ISO/IEC 14496-3/Amd1 (MPEG-4 version 2) Audio Part.

MPEG-4 CELP operates in a narrowband mode (8 kHz sample rate) or a wideband mode (16-kHz sample rate) and achieves bit rates in the range of 4 to 12 kbps for a narrowband configuration or approximately 11 to 24 kbps in a wideband configuration. In addition, MPEG-4 CELP supports scalable coding that allows multiple low-bit-rate streams to be embedded in a single stream such that a lower quality rendering can be played back if the full rate bitstream is not completely available.

MPEG-4 CELP is one of the coding schemes specified for Digital Radio Mondial (DRM), where it is used to enable high-quality speech coding, either for delivering good-quality speech at low bit rates, for running multiple speech applications over one DRM channel or for providing extremely robust transmission of speech.

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