My roommate with an iPhone wants to cut the cable on the headphones above the built in mic that came with it and replace the original earbuds with the earbuds in his Apple In-Ear headphone earbuds. Does anyone know if this would work?

I'm pretty sure they are going to be the same impedance, the question is does the signal line for the mic end at the mic or does it for some reason pass through to the buds.