Seeing "No Service" or a missing signal icon on your OnePlus 13 Pro is one of those instant headaches. You're suddenly cut off from calls, texts, and mobile data. The good news is that most of the time, this is a temporary glitch you can fix yourself without much fuss.
I'd start with the simplest fix first. Grab your phone and perform a force restart. Press and hold the Volume Down button and the Power button together for about 10 seconds. Keep holding until you feel the device vibrate and the OnePlus logo appears on the screen. This clears out any minor software hiccups that might be blocking the cellular radio.
Check the Obvious First
It sounds silly, but always double-check that Airplane Mode isn't accidentally enabled. Swipe down from the top of your screen to open the Quick Settings panel and make sure the airplane icon isn't highlighted. While you're there, also tap the mobile data icon to turn it off and then back on.
Your physical location plays a huge role. If you're in a basement, a large building, or a rural area, you might simply be in a dead zone. Try moving near a window or stepping outside to see if bars reappear. A quick reboot of the phone itself can also work wonders for temporary radio issues.
Reinsert Your SIM Card
A loose or dirty SIM card is a classic culprit for signal problems. You'll need the SIM ejector tool that came in the box with your OnePlus 13 Pro. Gently push it into the small hole on the SIM tray, usually on the bottom edge of the phone, to pop the tray out.
Carefully remove the SIM card and give the gold contacts a look. If you see any dust or debris, gently wipe them with a soft, dry cloth. Blow into the SIM tray slot as well to clear any lint. Then, reseat the SIM card firmly into the tray and slide it back into the phone until it clicks.
Verify Your Network and Roaming Settings
Sometimes the phone's network selection gets stuck. Open the Settings app and go to Mobile network. Tap on your SIM card (if you have dual SIMs) and then look for the Network operators option. Select Choose automatically to let your phone search for and connect to your carrier's best available signal.
If you're traveling or near a border, your phone might need data roaming enabled to latch onto a partner network. In the same Mobile network settings menu for your SIM, you should find a Data roaming toggle. Turn it on, but remember that using roaming can lead to extra charges from your carrier.
Reset Your Network Settings
This is a more thorough step that won't delete your personal files, but it will clear all your network-related configurations. It's great for fixing corrupted connection data. Head to Settings > Additional settings > Backup & reset.
Here, tap on Reset phone and then select Reset Wi-Fi, mobile & Bluetooth. Confirm the action. Your phone will restart, and you'll need to reconnect to Wi-Fi networks and re-pair Bluetooth devices, but it often resolves persistent cellular issues.
Update Your Access Point Name (APN)
The APN is like the gateway address that tells your phone how to connect to your carrier's internet. An incorrect APN can leave you with bars but no data. Go back to Settings > Mobile network, select your SIM, and tap on Access Point Names.
If the list is empty or looks wrong, you can usually tap the three-dot menu and select Reset to default. If that doesn't work, you'll need to get the exact APN settings from your carrier's website or customer service and enter them manually by tapping the '+' icon.
Check for Software Updates
OxygenOS updates frequently include patches for connectivity and radio performance. Keeping your OnePlus 13 Pro updated is one of the best things you can do for its overall health. Go to Settings > About device > OxygenOS version.
Tap on the icon at the top right (it looks like three dots or a download arrow) to check for updates. If an update is available, download and install it. Make sure your phone is connected to Wi-Fi and has a good charge before starting the update process.
Use the Phone Information Menu
Android has a hidden diagnostic menu that lets you interact directly with the radio. Open your Phone dialer app and type *#*#4636#*#*. This should open the "Testing" menu. Tap on Phone information.
In this menu, you can see detailed info about your signal strength. Look for a button that says Run Ping Test or Turn off radio. You can try toggling the radio off and then back on. Near the top, there's also a dropdown menu for "Set preferred network type." Try selecting NR/LTE/WCDMA/GSM (Auto) for the broadest compatibility.
Inspect Your Case and Disable VPNs
A very thick or metal phone case can sometimes interfere with antenna reception, especially if it wasn't designed for the OnePlus 13 Pro. Try removing your case for a few minutes to see if your signal improves. It's a long shot, but it has solved the issue for some people.
If you use a VPN app for privacy, it could be malfunctioning and blocking all network traffic. Go to Settings > Connection & sharing > VPN. Disable any active VPN connections here. You can also go to your app list, find the VPN app itself, and force stop it or clear its cache.
Contact Your Carrier
If you've tried everything on the phone itself, the problem might be on your carrier's end. There could be a local tower outage, maintenance work, or an issue with your account. The quickest test is to put your SIM card into another compatible phone.
If the other phone also gets no service, you know the issue is with the SIM or the carrier. Give your provider's customer support a call. They can check for outages, refresh your connection on their network, and advise if you need a replacement SIM card, which they can usually send out or provide in a store.