Typical Icom MIC Connector. Image courtesy Icom Inc.

MODULAR JACK PINOUT (Front View)
Pin 1.   +8 volts
Pin 2.   Frequency up/down
Pin 3.   AF out
Pin 4. PTT
Pin 5.   Mic Ground
Pin 6.   Mic Input
Pin 7.   GND
Pin 8.   Squelch switch