I'm planning on buying a factory unlocked iPhone from eBay, then cutting my full-size StraightTalk SIM card I use on my iPhone 3Gs, and using it with the iPhone 5. I have an AT&T-compatible StraightTalk SIM card, which is no longer sold, so I can't screw up cutting it. How hard is it to cut it successfully? Is this a feasible plan in general? Thank you.