Hey @hartmank48! I checked in with the S.M.A.R.T. crew and I hear they've answered most of your questions. We do not charge for roaming on domestic towers within the US, but there are limits for roaming usage. You can find out more about that on our Roaming FAQ page
SeaWolf Sprint Community Manager & Customer Advocate Captain of the Vicious Cream-puff I encourage you to post your questions on the community, give Kudos when earned and always mark the correct answer as "Accepted Solution".