Yep, that's why the iPhone 4 has a microphone on the top next to the headphone jack.
Actually, the iPhone 4's extra microphone is to reduce noise for the person you are talking to. The iPhone 5 uses noise cancellation to also reduce background noise for you. Similar to how Bose or any other noise canceling headphones work. It's a feature that many don't realize is there.
Maybe the commercial didn't explain it as well as it should have.