How Check iPhone is Unlocked or Locked Via IMEI
How to unlock your iPhone
If You are looking how can unlock your iPhone, so you can use it with different carriers network. An unlocked phone is sometimes called a SIM Free or contract free plan phone.
First you can check online your iPhone imei to understand the state of your idevice. If is also clean with no iCloud. Also find the original carrier network locked. Check iPhone Unlock Status. Also apple guide you what you need to do to unlock your iPhone using this tutorial.
imei.info/ have a limit free service , you can check for imei information , carrier lock , iCloud status for clean mode, lost, erase. Also for blacklist imei check.