By Aidan Malley

Published: 06:20 PM EST

Apple says it has shipped four million iPhones since launch. With just short of two million AT&T customers using the device, however, one analyst suggests that a large number of the handsets are mysteriously unaccounted for.

Toni Sacconaghi of Bernstein Research observes in a note to investors that the gap between Apple's shipment claims, AT&T's subscription numbers, and European projections should leave roughly 1.4 million of the devices to be split between unlocked devices and those simply idling on store shelves.

While European sales have not been detailed in full, they're unlikely to have represented the majority of that remaining amount, the researcher says. If claims of 190,000 UK iPhone sales are accurate and are combined with official results of 70,000 French models and a similar number from T-Mobile Germany, Apple will have sold approximately 350,000 devices outside of the US -- well short of filling the gap left by AT&T's customer base.

The gray market for unlocked iPhones is also unlikely to explain the difference, Sacconaghi says. For its summer quarter, Apple reported 250,000 likely unlocked iPhones in its sales figures, or about 18 percent of the inventory shipped at the time. Assuming about 20 percent of iPhones were unlocked -- a 'generous' amount, the analyst adds -- this would only account for about 750,000 of the 1.4 million phones and leave about 670,000 of the phones "missing in action," according to the note.



For Sacconaghi, this points to the potentially worrying prospect that a significant number of iPhones remain in Apple's channel inventory, whether at its warehouses or at retail locations. If all the 670,000 handsets were to land at the carrier-specific distribution points around the world, this would leave as many as 150 iPhones at each store by the start of 2008.

This excess stock may be partly absorbed by Apple's own inventory but could run higher still if the company has successfully reduced the number of iPhone unlocking attempts through successive firmware updates or by controlling the number of phones sold at once. If just 10 percent were sold unlocked in the last quarter, it would leave more than one million iPhones unexplained and as many as 238 iPhones unsold per store.



Apple has not provided an explanation for the apparent shortfall. Regardless, the Bernstein report suggests the possibility of cooling demand for the iPhone that is at least partly masked by official shipment numbers, which only indicate the number of products leaving the company's factories.

"This is negative in two ways," Sacconaghi elaborates. "It indicates end-user demand for iPhone is lower than many investors may think based on Apple's [four million] sales figure... and it points to slower iPhone sales in the current quarter, since much of this inventory is likely to be drawn down."