Request the sim unlock code for your Samsung Galaxy S9 or S9+ When asked, provide them with your phone’s IMEI number The unlock code will by email to you in 2-5 days ...

For any other device, an unlock code will be sent to you via email. Use the code to unlock the phone. In a few cases, O2 may need to contact the device manufacturer to get the unlock code.

Huawei's HONOR sub-brand is issuing bootloader unlock codes to users once again, via the XDA-Developers community. But the new approach pales in comparison to the original process.