I would certainly suspect that IDing potential sellers would generally be enough to scare away most would-be criminals. However, this is not going to stop all of them. There is always the potential of the "third-party" transactions. Inasmuch, there is little that you can do to prevent it 100% if you buy used phones. One of the companies for which I work doesn't ID customers, instead they check the phone's ESN on Verizon's website. The other is a pawn show / cell phone provider, so they not only ID, but also enter the information from that ID into the computer catalog where it will be stored permanently. In both cases, we've ended up with stolen phones.
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