Where are you located?
First step would be to call Sprint to inquire about any outages they may or may not be experiencing in your area. If they say there are no outages in your region then it could be two things;
1) Network Vision is in the process of rolling out, which should make you super happy.
2) Tower is super overloaded, which should make you super unhappy.
That is how I would go about your situation, imho.