Unlocking a device bootloader lets you install custom recoveries, ROMs, or root access. The exact steps vary by manufacturer and model, but the general process below covers methods that work when you don’t have a SIM card.
Important: unlocking the bootloader may void warranty, erase all data, and can brick your device if done incorrectly. Back up any data you can before proceeding. how to unlock bootloader without sim card
Some manufacturers allow bootloader unlocking without a SIM. How to unlock a bootloader without a SIM
Tools like MTK Client (for MediaTek) or Qualcomm Tool can sometimes bypass SIM requirement by reading/writing to nvdata partition directly. Turn off the phone
You can do this without a SIM card installed.
adb reboot bootloader.