Neither AT&T nor Apple has ever admitted how long the exclusive sales arrangement is for the iPhone. Despite their silence, at least one person strongly believes the deal will end in June 2010, which means the iPhone will then become available via more carriers in the U.S.Even though the iPhone has been a success story in the U.S., it could have been even more successful if AT&T weren't the only network operator selling the device. Since June 29, 2007, if U.S. customers wanted an iPhone, they had to purchase one with an AT&T contract. Brave users many have purchased their iPhones outright and hacked them to work on other GSM networks, but all the "legit" iPhones are still locked to AT&T.

Since the iPhone was first announced, the public has wondered how long the exclusivity deal between Apple and AT&T is. Why? Because people want to be able to use the iPhone on networks other than AT&T's. According to Broadpoint AmTech's analyst Brian Marshall, they'll be able to starting in June 2010.

Marshall was recently interviewed on Bloomberg TV, and mentioned some interesting points. CNN's BrainStormTech blog reports that Marshall said:

• The contract that gives AT&T (T) exclusive access in the U.S. to Apple's (AAPL) iPhone expires in June 2010.
• Apple is now getting a $450 subsidy from AT&T for each iPhone it sells; after June, that subsidy will be reduced to $300 for all carriers, domestic and international.
• The 4% of AT&T subscribers who use the iPhone consume roughly 40% of the network's bandwidth.

Interesting stuff, but many of the comments under the BrainStormTech post claim that Marshall doesn't know what he is talking about. The comments openly dispute the facts and say that Marshall is flat-out wrong.

I can't say if he is or if he isn't. "Three years" has always been the guess that analysts and the media keep returning to on the subject of iPhone exclusivity, so his basic premise makes sense to me.

What's most interesting is to note that the iPhone's availability in France recently expanded beyond just a single carrier -- and sales shot way up. With sales taking a dramatic turn like, Apple is surely counting down the days to when it is no longer beholden to AT&T.

If you want to see Marshall's spot on Bloomberg TV, here it is: