name:         HT9305C
function:     5-Memory Tone/Pulse Dialer
package:      DIP20,20
manufacturer: Holtek

       +--()--+
   C1B | 1  20| R4B
   C2B | 2  19| R3B
   C3B | 3  18| R2B
   C4B | 4  17| R1B
   C5B | 5  16| MODE
    X1 | 6  15| DTMF
    X2 | 7  14| POB
XMUTEB | 8  13| HKSB
   VSS | 9  12| VDD
  DOUT |10  11| CLOCK
       +------+


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