* This tutorial applies to only original Samsung phones.
An unknown Baseband is as a result of a corrupted EFS partition. The EFS holds the phone's IMEI and other radio information. To check the phone's Baseband, navigate to Settings > About > Baseband. Check the IMEI by dialing *#06#
You'll usually know you've been hit by the NULL IMEI / Unknown Baseband when you observe:
* Bluetooth address is unavailable
* WIFI connection will work inconsistent
* Constantly rebooting
* Fake IMEI or Null IMEI # (normally - 004999010640000)
* Null Serial number -(0000000)
* Unable to register to network
When you encounter an unknown Baseband and NULL IMEI, the first thing you need to fix is the unknown Baseband by flashing the Stock ROM / firmware for the exact phone model using Odin @ https://www.hovatek.com/forum/thread-519.html
Once that is done, you can then write an IMEI to the phone