earpiece and microphone won't work, but bluetooth handsfree does

I have an iPhone 3G and the earpiece and microphone (what you hear and speak into) do NOT work. I connected a jawbone handsfree and it works perfectly, as well as headphone handsfree.

I tried plugging and unplugging handsfree headset in hopes to trigger the phone and realizing it what mode it was in...didnt work.

I have reset all the settings, including a restore..still no luck.

Any ideas?! Thanks