<i>The ability to roam onto a different network? Yes, T-mobile doesn&#x27;t cover everywhere, but has roaming agreements to fill the gaps in coverage.</i><p>There&#x27;s a caveat that data roaming is pretty restricted.  My wife visited Bozeman, MT, and was limited to, I think, 10 megs of data, which went very quickly.  On the other hand, in the UK T-mobile had unlimited but somewhat slow data at no extra cost.