using speakerphone with headphones?

[lazyboy0172]

is there any way to use the speakerphone mic. while headphones are plugged into a cdma touch pro 2? i was driving home from work today and decided to plug my phone into the car stereo for the first time to listen to music- when suddenly i got a phone call. I answered without picking up the phone and it was a nice hands-free solution that didn't cost me a thing, or at least i thought it would be. The person on the other end couldn't hear a thing, and i had to lift the phone up to my ear to speak.

Has anyone thought of this before? do you know anything i could do to make it happen?

Thanks,
lazyboy.