The device will show "No Service" or "Emergency Calls Only" because the modem cannot verify the IMEI. Null/Generic IMEI:
If you have , flashing the full stock firmware with a PIT file (re-partition) may rebuild EFS – but this rarely works if hardware IDs are lost. Usually, service center repair with a certificate box is required. efs file samsung
Samsung integrates a hardware-level security solution called . The EFS partition is tightly linked to the Knox warranty bit and the device's secure boot chain. Any official or unofficial change to the system can corrupt the EFS linkage. The device will show "No Service" or "Emergency
Calibration data for cellular antennas and modem settings. Samsung integrates a hardware-level security solution called
Because this data is unique to your specific hardware, if the EFS partition is corrupted (often during rooting or flashing custom ROMs), your phone cannot simply be "reset" to fix it.