2.5mm headset pinouts

[Guest crozz]

Hi All.

I am building an adaptor for a motorcycle headset that I already have.

Does anyone know what the pinouts are for the 4-pole 2.5mm headset socket?

I am also interested in how the 'answer/talk' button works on the standard headset. There are only 4 pins for the headset (mic, left, right, ground), so I assume that it grounds one or more of these.

If anyone has the details, I'd be very gratefull.

Thanks, Crozz

i-mate SP5, Australia.