Seeing a "No SIM" or "SIM not detected" message on your CMF Phone 2 Pro is a real roadblock. You can't make calls, send texts, or use mobile data. The good news is that with Nothing OS 3.0, most of these issues are caused by simple glitches you can fix in a few minutes.
Start With a Force Restart
Before you do anything else, give your phone a fresh start. This clears temporary software bugs that can confuse the SIM reader. Press and hold the Power button for about 10 seconds until you feel a vibration and see the screen go black. The phone will restart on its own.
This is the single most effective first step for the CMF Phone 2 Pro. I've seen it resolve the "No SIM" error more often than not, especially after a recent app update.
Check the SIM Card and Tray
If a restart doesn't work, the next step is a physical inspection. You'll need the SIM ejector tool that came in the box. Power the phone off completely first.
Gently push the tool into the small hole on the SIM tray, usually on the bottom edge of the phone. Pull the tray out and carefully remove the SIM card. Look at the gold contacts on the card for any scratches, dirt, or corrosion.
Use a clean, dry microfiber cloth to gently wipe the contacts. Blow any dust out of the SIM tray slot on the phone itself. When reinserting, make sure the SIM card is seated correctly in the tray and that the tray slides in smoothly without force.
Toggle Airplane Mode and Verify SIM Status
Swipe down from the top of your screen twice to open the full Quick Settings panel. Tap the Airplane Mode icon to turn it on, wait about 10 seconds, then tap it again to turn it off. This forces the phone's modem to re-establish a fresh connection to the network.
Next, go into your settings to make sure the SIM is actually enabled. Open Settings > Network & internet > SIM cards. Here, you should see your SIM listed. Make sure the toggle next to it is switched on. You can also tap on the SIM to see more details about its status.
Update Your Software
Nothing frequently releases updates for Nothing OS that can fix connectivity bugs. It's worth checking if you're running the latest version. Go to Settings > System > System update.
Tap "Check for update." If an update is available, download and install it. Your phone will restart as part of the process. This can resolve issues that appeared after a previous update or app installation.
Reset Your Network Settings
This is a more thorough step that clears all your saved Wi-Fi networks, Bluetooth pairings, and cellular network configurations. It won't delete your personal files like photos or messages.
To do this, navigate to Settings > System > Reset options. Tap on Reset Wi-Fi, mobile & Bluetooth and confirm. After the reset, you'll need to reconnect to Wi-Fi and re-pair Bluetooth devices, but it often fixes stubborn SIM detection problems.
Check Your APN Settings
Incorrect Access Point Name (APN) settings can sometimes prevent your SIM from registering properly on the network, even if it's detected. These settings are usually configured automatically, but they can get corrupted.
Go to Settings > Network & internet > SIM cards. Tap on your active SIM, then select Access Point Names. If the list is empty or looks wrong, you need to reset it.
Tap the three-dot menu in the top right and select "Reset to default." If that doesn't populate the correct settings, you'll need to get the exact APN details from your mobile carrier's website or customer support and enter them manually by tapping the "+" icon.
Try Manual Network Selection
By default, your phone automatically connects to your carrier's network. Sometimes this process can fail. You can manually select the network to force a connection. Go back to Settings > Network & internet > SIM cards and tap your SIM.
Look for an option called "Network operators" or "Carrier." Tap it, then tap "Search networks." After a moment, a list of available networks will appear. Select your carrier's name from the list. If it registers successfully, your SIM issue might be resolved.
Test the SIM in Another Phone
This is the best way to figure out if the problem is with your CMF Phone 2 Pro or the SIM card itself. If you have access to another unlocked Android phone, power it off, insert your SIM, and turn it back on.
If the other phone also says "No SIM" or doesn't recognize the card, the issue is definitely with the SIM. You'll need to contact your carrier for a replacement SIM card, which they usually provide for free or a small fee.
Clear the SIM Toolkit Cache
System apps that manage the SIM can accumulate corrupted cache data. You can clear this cache without harming your data. Open Settings > Apps > See all apps.
Tap the three-dot menu and select "Show system apps." Now, scroll through the list or use the search bar to find "SIM Toolkit" or "STK." Tap on it, then go to Storage & cache. Tap "Clear cache." Restart your phone afterward and check if the SIM is detected.
Consider a Factory Reset
This is your last resort for a software fix. A factory reset will erase everything on your phone, returning it to its original out-of-the-box state. You must back up all your important data first using Google Drive or another method.
To perform the reset, go to Settings > System > Reset options. Select Erase all data (factory reset) and follow the prompts. After the phone reboots, set it up as new and test the SIM card before restoring your backup. If the SIM works on a fresh system, the problem was a deep software conflict.