The Case of the Missing iPhones

According to Apple, they have shipped four million iPhones since launch. AT&T customers comprise of just under half that amount, which leaves a large number of handsets unaccounted for. According to Toni Sacconaghi of Bernstein Research, the sum of AT&T’s subscription numbers and European projections would mean around 1.4 million iPhones are sitting idly on store shelves or being sold as unlocked devices. The latter currently stands at approximately 250,000 units, so that leaves approximately more than half a million iPhones that are missing in action. What are some of your theories behind this? Does this mean that HTC, having sold (not shipped) more than 2 million HTC Touches is actually the big winner here?