As Apple Inc. prepares to release its newest iPhone Tuesday, the terms it has squeezed from Sprint Nextel Corp. reveal the leverage it has over the telecom companies that once ran the show.

Sprint, the No. 3 U.S. wireless carrier, is making a multibillion-dollar gamble that access to the iPhone will be the ticket to a turnaround. Sprint has committed to buy at least 30.5 million iPhones, even though it would likely lose money on the deal until 2014, according to people familiar with the matter.

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