There are 3 methods to check if iPhone is Unlocked or Locked. You can do it by using two different SIM-Cards or you can find the SIM-Lock status without using a SIM-Card. The procedure for telling if an iPhone is Unlocked is very quick and easy, through iPhone’s Settings or an iPhone Unlock Check Service. Read more
Is my iPhone Unlocked?
Check IMEI iPhoneiPhone Unlock