This part is a kind of semiconductor called MT8870.
Function of this product has ISO2-CMOS Integrated DTMF Receiver.
Manufacturers : Mitel Networks Corporation
Image and pinout :
Some of the text within the PDF file :
® ISO2-CMOS MT8870D/MT8870D-1 Integrated DTMF Receiver Features • • • • • • • • Complete DTMF Receiver Low power consumption Internal gain setting amplifier Adjustable guard time Central office quality Power-down mode Inhibit mode Backward compatible with MT8870C/MT8870C-1 ISSUE 3 May1995 Ordering Information MT8870DE/DE-1 18 Pin Plastic DIP MT8870DC/DC-1 18 Pin Ceramic DIP MT8870DS/DS-1 18 Pin SOIC MT8870DN/DN-1 20 Pin SSOP MT8870DT/DT-1 20 Pin TSSOP -40 °C to +85 °C Description The MT8870D/MT8870D-1 is a complete DTMF receiver integrating both the bandsplit filter and digital decoder functions. The filter section uses switched capacitor techniques for high and low group filters; the decoder uses digital counting techniques to detect and decode all 16 DTMF tonepa [ ... ]