name:         HT9170D
function:     DTMF Receiver
package:      SOP18,18
manufacturer: Holtek

     +--()--+
  VP | 1  18| VDD
  VN | 2  17| RT/GT
  GS | 3  16| EST
VREF | 4  15| DV
 INH | 5  14| D3
PWDN | 6  13| D2
  X1 | 7  12| D1
  X2 | 8  11| D0
 VSS | 9  10| OE
     +------+


This pinout came from the Chipdir:
http://www.chipdir.org/