... speech compression and decompression, such as the 32kbps ADPCM, 64kbps PCM. Provided the reliable buttons (DTMF) detection, the recording and playback ... 32K buffer: an uploaded file. -Digital voice: A/u my PCM, ADPCM. -Data rate: 64Kbps, 32Kbps, 16KbpsDTMF code: 0-9, *, #, A ...