Below are a few links to get you to looking up coverage areas and other information of note.
Where can I look up if the country I am traveling to is has coverage for International Roaming?
There is a tool to look up countries here.
How can I find out if the device I own can roam in other countries?
There is a list here. Also, if you do not see your device listed there, the page provides a link to the International Roaming Group for further questions.
How can I find out if my plan includes international roaming or if I need to purchase the additional service?
There is a wealth of information about traveling and roaming on the International Roaming page.
How do I report roaming issues?
You can contact Sprint in several ways as explained on this page.