3.12 Headset Interface
This phone chooses a 5 pin type headset which has 6 electrodessuch as
HEADSET_SPK_OUT_P, HEADSET_MIC_P, JACK_DETECT, HEADSET_SPK_OUT_N,
RADIO_ANT. This type supports stereo sound
Switching from Receiver to Headset Jack
If jack is inserted, JACK_DETECT goes from high to low.
Audio path is switched from receiver to earphone by JACK_DETECT interrupt.
Switching from Headset Jack to Receiver
If jack is removed, JACK_DETECT goes from low to high.
Audio path is switched from earphone to receiver by JACK_DETECT interrupt.