To check if your mobile phone is already unlocked, insert into it a sim card from a different network. For example, if your phone is with EE, insert a Vodafone or Three sim card into it.
If your phone connects to the different network then your phone is unlocked: please verify that you actually see the different network signal bars on your phone. If there are any error messages, or your phone displays "SOS Only" or "Invalid SIM", then this means your phone is not unlocked.
[You must use a different network sim card. Some providers actually use the same network - they are call MVNOs.]
You cannot use the USA SIM card to test if your phone is unlocked because the USA SIM card will not connect to any network in the UK.
Please do not call or email us to ask us if your phone is unlocked. The above information is the ONLY way to be 100% certain that your phone is unlocked. If you're not sure if your phone is unlocked, then neither will we!