Sorry if this is a silly question - my brother has an S2 with out-of-the-box, custom ROM, not ever flashed or rooted, etc. He has just been told he has to work in Spain for the forseeable futre but wants to come home at weekends. He also wants to keep his S2.
If he roots and flashes his phone, will he be able to buy a Spanish SIM from any Spanish network for use in Spain, and just replace it with his own SIM when he comes back here? In other words, does a root and flash of a phone make it fully internationally unlocked so that he doesn't get any extra charges from either Spanish or UK networks?