Imagine the sheer number of embarrassing incidents at work you could have avoided, if people weren't designing things with "protect you from yourself" mentalities!
Welcome to Android Central! I'm sorry, I don't quite understand. When you plug in headphones that have a mic, the handset's mic won't work, and sound will play over the headphones, not the main speaker. If you plug in headphones without a mic, then you can still use the phone's mic when calling.