Speak on MSN-Skype-YIM using earphones!

Ok, I had no idea where to put this. So I just put it here.
Last night, I plugged in my earphones, tweaked a few settings, and found out that you can speak through earphones????

Has anybody done that?
By earphones, I don't mean a headset or anything... I mean earphones... The usual ones you use for your MP3.


If it turns out that nobody has heard of such a thing, I’ll write a tutorial.

 

Yup....If you hook your headphones pin in Mic's port then it will work exactly like a Mic...!

 

but how is that possible from, a umm. Technical point of view???

 

coz companies put Mic elements in the Headphones as well now these days..

 

and most people don't even know this :S?