The BU8872 and BU8872FS are DTMF receiver ICs developed for use in telephone answering machines, and convert 16 different types of DTMF signals into 4-bit binary serial data. In addition to a compact 8-pin DIP (BU8872) or 16-pin SSOP (BU8872FS) package, these receivers feature a wide dynamic range, eliminating the need for an external input amplifier. Expertise from a number of companies has been incorporated into these products to enable guard time control through a host microcomputer.