Sprint-Nextel, the No. 3 wireless carrier, acknowledged that selling Apple iPhones may be a costly bet: the carrier said it may require as much as $7 billion to help pay Apple for them.

Now selling Apple's iPhone 4S, four years after AT&T started to sell the first one and a year after Verizon Wireless started to sell the iPhone 4, Sprint said it will have to pay Apple as much as $15.5 billion through 2015 to cover equipment costs.

The Overland Park, Kan.-based carrier, which also has a substantial wireline business, reported a third-quarter loss of $301 million, or 10 cents a share, better than last year's loss of $911 million, or 30 cents. Revenue rose slightly to $8.3 billion.

Sprint, though, hasn't reported a profitable quarter since 2008, so its cash may run short in order to pay Apple before customers start activating its network. On Wednesday, it said it had increased its credit line by $150 million, to $2.24 billion. The company reported cash and equivalents of only $3.76 billion.

Also, the carrier acknowledged that it's selling the iPhone 4S for a loss. Priced at $199 in Sprint stores, the operator itself is paying Apple, based in Cupertino, Calif., as much as $200 more for the new product. Analysts believe Sprint may have to sell as many as 6 million iPhones a year to make a profit.

IPhone has an expensive contract but is worth every penny, Sprint CEO Dan Hesse told investors. Near-term, the CEO estimated initial iPhone sales will shave fourth-quarter earnings by as much as $800 million.

Sprint didn't issue a forecast for how many iPhone 4S units it expects to sell this quarter. The company reported having about 53 million wireless subscribers, up only about 1.5 million since June.

Sprint has joined the U.S. Justice Department's suit to prevent the takeover of T-Mobile USA by AT&T, claiming it would bar competition. Judge Ellen S. Huvelle Monday allowed the company limited access to government documents used to bring the suit.

Meanwhile, Sprint said it was renegotiating terms of its investment in Clearwire, the national high-speed carrier. Sprint has long been its majority owner.

Sprint shares fell three percent in late trading to $2.62, giving it a market capitalization of $7.85 billion.

contact David Zielenziger at d.zielenziger@ibtimes.com