Freedompop AT&T and Global SIM question

So this may be a dumb question. I have the FreedomPop AT&T sim in my phone right now. I also have a Freedompop Global sim lying around. If I pull out the AT&T sim and put in the Global sim, will I have to update the APN and stuff, or is it a painless process? (By the way, the phone is a MetroPCS phone, don't know if that is relevant).