That makes sense; the odds of bumping at the same place, at the same time, and with similar enough motion vectors should be small enough to give uniqueness. Th

That makes sense; the odds of bumping at the same place, at the same time, and with similar enough motion vectors should be small enough to give uniqueness. That said, every phone I've ever owned in Japan has a little IR port, and you can send your contact info across very easily, even between different carriers.