name:         HT9315AI
function:     5-Memory Tone/Pulse Dialer
package:      DIP18,18
manufacturer: Holtek

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


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