Your iPhone displays that “Your SIM sent a text message.” and you don’t know why. When this happens, there’s usually an issue between your iPhone and your wireless carrier.
Please try the following troubleshooting steps one at a time-
1) Force Restart the phone:
- Press and quickly release Volume UP button
- Press and quickly release Volume DOWN button
- Press and Hold the SIDE button until an Apple logo appears then release the Side button (Can take up to 20 seconds. DO NOT release Side Button when invited to Slide Power OFF)
2) Reset Network Settings:
- Open Settings ➔ General ➔ Reset ➔ Reset Network Settings - (This will require you to enter all WiFi passwords again as you connect to previously known WiFi networks.)
3) Please call your Carrier and explain your concern and see whether they can reset your account.
Axel F.