Medicare Part B Requirement?

I have heard that ALL US citizens need to enroll in Medicare Part B by March 31, 2015, or face penalties (higher rates when you sign up later). I can’t phone from my overseas location and, thus, I need to reach Obama Care/ the ACA by e-mail. Medicare Part B cannot be used at my overseas location. I was originally told that the penalty in increased rates (+10% per each 12-month period of non-enrollment) would not apply to me as long as I continued to reside overseas. Now I hear a differently. I would like to discuss this by e-mail with someone. I cannot call to the USA from my location overseas and e-mail is the only means of communication.