Seeing a "Not registered on network" message on your Samsung Galaxy S24 is a real roadblock. It means your phone can't find or connect to your carrier's signal, so calls, texts, and mobile data won't work. This usually happens because of a temporary software hiccup, a network setting that got scrambled, or a problem with your SIM card.
Before you worry about anything serious, start with the quickest fix. Pull down the notification shade twice to open the Quick Settings panel and tap the Airplane Mode icon to turn it on. Wait about 15 seconds, then tap it again to turn it off. This forces your phone's modem to completely disconnect and then search for the network again, which often solves the problem right away.
Restart Your Galaxy S24
If toggling Airplane Mode didn't work, a full restart is the logical next step. This clears the phone's memory and reloads all the system processes, including the one that handles network registration. Just press and hold the Side button and either volume key, then tap "Restart" on the screen. Wait for the phone to fully boot up and see if the signal bars return.
For a more thorough refresh, you can perform a force restart. Press and hold the Volume Down button and the Side button together for about 10 seconds. You'll see the Samsung logo appear as the phone rebarts. This can clear deeper glitches that a standard restart might miss.
Check Your SIM Card
A loose or dirty SIM card is a surprisingly common culprit. First, power off your S24 completely. Use the SIM ejector tool that came in the box (or a small paperclip) to pop open the SIM tray on the bottom edge of the phone.
Carefully remove the SIM card and give both the gold contacts on the card and the inside of the tray slot a visual inspection. If you see any dust or debris, gently blow on it or use a soft, dry cloth to clean it. Reinsert the SIM card, making sure it's seated firmly in the tray, and push the tray back into the phone until it clicks. Power the phone back on.
Verify Your Carrier Account Status
Sometimes the issue isn't with your phone at all. If your prepaid plan has expired, your postpaid bill is overdue, or there's an account issue, your carrier will suspend service. Your S24 will then show as not registered.
Try logging into your carrier's account portal from a computer or another phone, or give their customer service a call. Confirm that your line is active and in good standing before spending more time troubleshooting the device itself.
Update Your Phone's Software
Samsung frequently releases updates for One UI that include fixes for connectivity bugs. An outdated software version could have a known issue that's already been patched. To check, go to Settings > Software update and tap Download and install.
Make sure you're connected to Wi-Fi, as these updates can be large. After the update installs and your phone restarts, it will re-register on the network, potentially fixing the problem.
Reset the Network Settings
This step clears all your saved network configurations, including Wi-Fi passwords, Bluetooth pairings, and cellular network settings. It's a great way to wipe out any corrupted data that's preventing a proper connection. You won't lose personal files like photos or messages.
Go to Settings > General management > Reset. Tap on Reset network settings. You may need to enter your PIN or password. Confirm the reset and let your phone restart. Afterward, you'll need to reconnect to Wi-Fi networks and re-pair Bluetooth devices, but your cellular connection should attempt a fresh start.
Manually Select Your Network Operator
Your phone might be trying to automatically connect to a network that's having temporary issues. You can force it to search for and connect to your specific carrier manually. Open Settings > Connections > Mobile networks.
Tap on Network operators. Turn off the "Select automatically" option. Your phone will search for all available networks. When the list appears, select your carrier's name from it. Wait a moment for the registration to complete.
Change the Network Mode
In areas with spotty 5G coverage, your S24 might struggle to register on the newer network. Switching it to prioritize 4G LTE can often provide a more stable connection. Head back to Settings > Connections > Mobile networks.
Tap on Network mode. Instead of "5G/LTE/3G/2G (auto connect)", choose the option that says LTE/3G/2G (auto connect). This tells your phone to skip searching for a 5G signal and connect to the strongest available LTE network instead.
Try a Different SIM Card
At this point, it's worth figuring out if the problem is with your SIM card or the phone itself. If you can, borrow a working SIM card from a friend or family member who uses a different phone on the same network.
Insert their SIM into your S24. If their SIM connects to the network without any "not registered" errors, then your original SIM card is likely faulty or damaged. You'll need to contact your carrier to get a replacement SIM. If the borrowed SIM also fails to register, the issue is almost certainly with your phone's hardware or software.
Perform a Factory Reset
This is your last resort software fix. A factory reset will erase all data, apps, and settings from your S24, returning it to its original out-of-the-box state. It will eliminate any deeply rooted software corruption. This will delete everything, so you must back up your important data first.
Once you've secured your photos, contacts, and files, go to Settings > General management > Reset > Factory data reset. Tap "Reset" and follow the prompts. After the reset is complete, set up the phone as new (don't restore a backup immediately) and see if it can register on the network. If the error persists after a clean factory reset, the issue is likely a hardware fault with the phone's internal modem or antenna, and professional repair would be the next step.
