IPhone unlockers a concern for Wall Street

Several Wall Street analysts raised questions Monday about the number of devices that have been modified to work with other wireless networks and what impact those modifications could have on Apple's
AAPL 122.25, +1.32, +1.1%) business in the future. Unlocking an iPhone allows the device to work on networks other than the one operated by AT&T
T 35.01, -0.01, 0.0%) , Apple's exclusive carrier partner in the U.S.
The questions stem from the companies' earnings reports last week. Apple claimed it had sold 3.7 million by the end of 2007, while AT&T said it had signed up nearly 2 million iPhone subscribers by year-end.
Those numbers leave approximately 1.7 million devices missing in action. Some of these were sold in Europe, though analysts believe that number falls somewhere between 300,000 and 400,000. And some of the devices may have been sold but not yet activated for telecommunications.
But analysts believe more than 1 million devices may have been sold and unlocked, accounting for as much as one-quarter of the company's total iPhone sales to date -- a number one analyst called "astounding."
The issue of unlocked iPhone units becomes more interesting because it brings up issues such as customer loyalty to a wireless carrier and how much impact would be felt at Apple in the coming years.