Please use other sim card to reset the R-Sim and enter the code, then use your sim card. After you reset the R-Sim card, you can select the auto option Sprint from the menu.
If this method does not working, then enter this IMSI Code 3160101
After you enter the IMSI code, tap Accept and restart your device. Now your device will connect to the network normally.
Note: Make sure you do not have a pin enabled on your sim card.