[vaporE]

My wife had this same issue. Nothing fixed it program wise. Meaning, Nothing I did to the phone (hard reset, soft reset, not installing anything) would fix it. We both ported our numbers from a different carrier about 1 year prior to this starting and it only affected her phone. Ultimately it was an issue with the MSID and Phone Number she had. We had to call Sprint and have them change both the MSID and give us a new phone number. Once we did that all is well.

Sure it sucked having to spam all her contacts with her new number but it was better than missing calls.