Note for people using the LTE on/off app:
Set the radio settings to CDMA auto (PRL).
The settings you have are explained as follows:
CMDA Auto (PRL):Same settings that 3G phones use. Automatically finds the best 3G connection based upon a preferred roaming list.
CDMA Only: Only locates CDMA (1XRTT) Connections. This will get you very slow data speeds.
EV-DO Only: Only locates CDMA (EV-DO) Connections. This is fine, but it can cause poor call quality and/or dropped calls as your phone will have problems authenticating on 1XRTT connections, which is what voice services use.
CDMA + LTE/EV-DO Auto: Will attempt to find any tower. Default connection.
***Warning: Use at your own risk. There have been cases that changing the radio setting can cause authentication errors on the network.***
If you are unable to connect after changing these, reboot your phone. If that doesn't work, change the setting back to CDMA + LTE/EV-DO Auto, reboot your phone, then call Verizon Tech Support at 800-922-0204 option 3 for Tech Support. Ask the agent to refresh your VLR (network profile), then turn off your phone, remove the SIM, wait 30 seconds then re-assemble and turn it back on.