The message SAYS it is from Sprint. However, the recorded message says "to protect your phone's security, I need to ask a few questions to be sure that I am speaking with the correct person." That sounds more like a scam or a bill collector. I did not wait to hear what the questions are.
All it is, is an automated voice message from Sprint saying you owe for your past month's billing amount. It's not a debt collector, it's just a reminder to pay your bill.