25-10-2017 11:57 AM - edited 25-10-2017 11:58 AM
You must have put the EE sim in a phone that is locked to another network. You will need to take the phone to an unlocker or ask the network who provided the phone to unlock it for you - a charge may need to be paid. In the meantime, try the sim in an unlocked phone.
25-10-2017 01:39 PM
@Christopher_G: You can't request an unlock through EE if the phone is locked to another provider, as seems the case here.