I recently rooted my Sprint HTC One M7, as well as my Samsung Mega SPH-L600. My goal was to get the phones unlocked to accept GSM sims. Both phones continue to show invalid sim no matter what. But I could switch the preferred network to CDMA and pick up the Sprint signal without any hassle. At some point, I had lost the Sprint signal. I have tried what seems like everything. Switching the network types. Turning roaming on and off. Switching sims. Installing different custom ROMS. Including CM10.1 in order to try switching from NV to RUIM. That did nothing. The weird thing is once in a while I will pick up the phone and see bars. And its the Sprint network. But a few seconds later, it will X out again. Before, I constantly had a signal full of bars, with a little triangle above it.
I would normally wonder if maybe a setting was changed. But why would this affect both of my distinctly different phones? Does Sprint block you if your phone is tampered? Or is it possible that if your service stays in roam that they will eventually block you? Just trying to find some answers here.