Unlimited Mobile to Mobile Calling Plans?

Bait & Switch Unlimited Calling Plans . . . 

Every carrier now has unlimited calling plans.  However, we are doing some research on which wireless carriers claim to provide unlimited calling plans but then charge a fee something else.  The old "bait and switch" billing method without full disclosure.  Cell phone calling plans have always been complicated and somewhat confusing as they are now being blended with unlimited data plans.  Most people expect a flat fee every month but then see charges that they don't recognize or understand.

Please tell us below under comments below which carriers trick you into paying for an unlimited plan and then charge you for something else without fully disclosing it.