Will my iphone 4 locked with orange work with a t-mobile sim?

My contract runs out next month and i'm wondering if its possible to use a t-mobile sim card in my iphone 4 that is locked with orange i'm curiouse because they have recently merged providers and i want to know if its possible can anyone help?

You will probably have to get the phone unlocked

Yes if you unlock your iPhone.

Well although i don't use either T-Mobile or Orange! Are these now not the same company? I think you should pop into the store and ask this question really but i though they were one and the same since they merged.

Yes because they merged they are both now "ee" so t-mobile will work in orange phone and vice versa