This part is a kind of semiconductor called MT8870D.

Function of this product has Integrated DTMF Receiver.

Manufacturers : Mitel

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 Applications • Receiver system for British Telecom (BT) or CEPT Spec (MT8870D-1) • Paging systems • Repeater systems/mobile radio • Credit card systems • Remote control • Personal computers • Telephone answering machine 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 integra [ ... ]

MT8870D PDF Datasheet Download