Below are some suggestions on troubleshooting connectivity problems:

1. Check to make sure the device is unlocked and compatible with the cellular network.
2. Confirm that the SIM card is inserted and activated on the cellular network.
3. Confirm that the cellular service is active, and no payment issues are preventing access.
4. Reset the network settings in the device’s menu.
5. Turn the device off and back on.
6. Check to make sure the antenna is working properly.
7. Check to make sure the network settings are enabled for the cellular network in the device’s settings.
8. Check the local service availability to confirm that the network is available in the local area.