name: HT9315BV function: 15-Memory Tone/Pulse Dialers with Volume Switches package: SKDIP24,24 manufacturer: Holtek +--()--+ S1 | 1 24| S2 HDI | 2 23| HDO C1B | 3 22| R4B C2B | 4 21| R3B C3B | 5 20| R2B C4B | 6 19| R1B C5B | 7 18| MODE/KT X1 | 8 17| DTMF X2 | 9 16| POB XMUTEB |10 15| HKSB VSS |11 14| VDD HFI |12 13| HFO +------+ This pinout came from the Chipdir: http://www.chipdir.org/