Several software packages are frequently used for this purpose:

Mobile repair technicians and electronics hobbyists frequently encounter budget feature phones and legacy smart devices that lose their International Mobile Equipment Identity (IMEI). This often happens after a bad firmware flash, a heavy hardware shock, or a corrupt file system.

While individual, standalone "Coolsand IMEI tools" exist as lightweight executables, the most reliable methods usually involve multi-functional GSM repair boxes or software suites. 1. Miracle Box (or Miracle Thunder)