Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_1 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8B117 Safari/6531.22.7) I work in construction and recently updated from a 3G to an iPhone 4. I would like to use my 3G while I am at work and my 4 all other times to lower the chance that I destroy my brand new phone. Is the new micro sim the only active sim? Can I turn off my 4 and turn on my 3G to use the 3G while at work? Or do I need to swap sims with an adapter?