If your Android mobile phone is displaying "Sim status: Phone number unknown" or similar issues, it can be frustrating, but there are several steps you can take to troubleshoot and potentially resolve the problem. Here's a step-by-step guide:

1. Restart Your Phone: Begin by restarting your Android device. Sometimes, a simple reboot can resolve minor glitches and refresh the network settings.

2. Check SIM Card: Ensure that your SIM card is properly inserted and secured in the SIM card tray. If it's loose or damaged, consider replacing it with a new one provided by your carrier.

3. Check Airplane Mode: Make sure that your phone is not in Airplane Mode, as this disables all wireless communication, including cellular connectivity.

4. Check Network Coverage: Verify that you are in an area with adequate network coverage. Poor or no signal reception can lead to this issue. Try moving to a different location to see if the problem persists.

5. Update Carrier Settings: Go to "Settings" > "System" > "Software Update" and check if there are any carrier updates available. These updates often include bug fixes and improvements related to network connectivity.

6. Check SIM Card Settings: Navigate to "Settings" > "Network & Internet" > "SIM cards" and make sure that the SIM card is recognized and enabled. You can also try switching between SIM slots if your phone has dual SIM card support.

7. Check Date and Time Settings: Incorrect date and time settings can affect network connectivity. Ensure that your phone's date, time, and time zone settings are accurate.

8. Network Reset: In some cases, resetting your network settings can resolve network-related issues. Go to "Settings" > "System" > "Reset" > "Reset Wi-Fi, mobile & Bluetooth." Confirm the action and restart your device.

9. Contact Your Carrier: If none of the above steps work, it's advisable to contact your mobile carrier's customer support. They can check if there are any issues with your account, SIM card, or network configuration on their end.

10. Factory Reset (Last Resort): If all else fails, you can perform a factory reset on your phone, but this should be considered a last resort, as it will erase all data on your device. Backup your data before proceeding.

11. Visit a Service Center: If the problem persists even after trying these steps, it may be a hardware issue. Consider visiting an authorized service center or your device's manufacturer for further diagnosis and repair.

Remember that some Android phones may have slightly different settings and menus based on their manufacturer and Android version, so the exact steps may vary. Always back up your important data before performing any major troubleshooting or reset procedures.