Actually, if you are domestically roaming, it is covered. However, the fastest speeds you will experience will be at 3G speeds (600 kbps), because you have a non-unlimited data allowance. If you had an unlimited data plan, you would experience 2G speeds (128 kbps).
I know how important it is to have service when you travel, Docmary. We certainly don't want you to incur any additional charges. Wadeowen307 is correct. Domestic roaming is included here in the U.S. If you leave the U.S., you will incur international charges. You can review our coverage map on our site using this link. http://spr.ly/660813D9w Does this help answer your question?