I have bought a used iphone4 for my 8 year old grandson. At initial ordering it stated it was locked to EE. I wanted an unlocked one but one wasn’t available at the price. It’s arrived without a SIM card inserted. Would an EE shop have and insert a general shop SIM to check if it is locked to EE. Thanks in advance. Bob.
Alternatively go into a Carphone Warehouse and ask them what your options are. With the hope of selling you a SIM or contract, I would have thought they would check it out for you, although probably not unlock it.