About carriers

in May last year I had to fish my daughter out of a swimming pool when she took her arm bands off and I had my phone in my pocket. I claimed on my insurance and they replaced it. But because it's not the same phone EE gave me they don't know if it's unlocked. So I have to try another sim from another network in it to see if it workes And then I ll see that it's unlocked? I think it's £8.99 to get it unlocked if it's not.i want to send this iPhone 6 to Greece to a friend of mine and needs to be ulocked....can anyone help me please? Thank you in advance!!!