I just bought a Verizon A1660 iPhone and was told by the rep that it's a world phone. He also said, to make sure it will be able to work with sims overseas, that I should activate it with my Verizon SIM before i try and use another SIM. Is this true? Or since i've never even opened the box, can i just take it overseas and pop in another sim initially and still be able to use other carrier sims. All help is appreciated.