Some iPhone 18 Pro and iPhone 18 Pro Max users report a serious problem after installing the latest iOS 27 update: their phones lose cellular service completely.
After installing the latest iOS 27 update, users noticed that their iPhones:
- No longer ask for the SIM PIN on restart.
- Don’t show a phone number in Settings > Cellular.
- Can’t make or receive calls or texts.
- Show ‘SIM Failure’ or ‘No Service’ at all.
- Display carrier services under SIM Applications, but tapping them does nothing.
- In some cases, eSIMs disappeared or couldn’t be re-added.
- Some users said Apple diagnostics flagged ‘Cellular RF Front end’ or motherboard failures, but they insist their phones worked perfectly before the update.
Fixes:
- Remove and reinsert SIM: If you’re using a physical SIM card, remove the SIM card and put it back in. Several users said this restored service.
- Reset Network Settings: Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings. Note: This will erase saved Wi-Fi networks, passwords and other network related settings like VPN.
- Check your eSIM line: For eSIM users, make sure the line is turned on:
- Open Settings > Cellular.
- Tap the cellular line you’d like to review.
- Check to see if it’s turned on. If the cellular line is off, tap Turn On This Line.
- Enable Data Roaming: A few users saw signal return immediately after turning roaming on:
- Go to Settings > Cellular > Cellular Data Options.
- Turn on Data Roaming.
- Wait with SIM removed: One user left the SIM out for a day, then reinserted it and got partial service back.
- Check Lockdown Mode: A handful of posts mentioned disabling Lockdown Mode helped, though others warned against using it unless necessary. When Lockdown Mode is turned on, 2G and 3G cellular support is turned off, although phone calls and plain text messages continue to work. Follow these steps:
- Go to Settings > Privacy & Security > Lockdown Mode.
- If it’s enabled, try turning it off and restart your device.
