You must figure out which service provider has locked your phone. This is because different service providers recommend different methods for unlocking your phone. A phone unlocking procedure for one service provider cannot work for a different provider and may even complicate the process further. Here is a helpful video to assist you in finding out which network your phone is locked to Checking Carrier Network. Checking which network your phone is locked to will also help you gather important information like the blacklist status of your phone, coverage status, and serial number.