What's this button for?
 

On the dash of my 2009 F150 is a button with an image of a telephone on it. I can't find reference of it in the owner's manual. What is it for? The salesman says it's a mute button for when you get a call on your cell phone. Since it doesn't mute anything, I figure he was just blowing smoke...

Did you read the manual? It is for the hands-free calling, if you have it installed. So basically it does nothing.