If resets don't work, a factory reset may resolve deep software conflicts.
This is the most effective standard fix. You are reinstalling the operating system without wiping your data (Home CSC). samsung a12 imei unknown
Some service codes attempt to rewrite the IMEI from a hidden backup: Dial *#0808# → Select → Connect to PC with QPST software. This method requires technical skill. If resets don't work, a factory reset may
Corrupt cache can confuse the modem. Power off → Press Volume Up + Power to enter Recovery Mode → Select Wipe cache partition → Reboot. If resets don't work