How iPhone came to rule US smartphone sales

Since Verizon Wireless broke AT&T's exclusive grip on the iPhone last year, several other phone carriers now offer Apple's popular smartphone. On Monday, T-Mobile said it will make a stronger bid for used iPhones from AT&T as Apple prepares to launch a new version.

Here's a look at how iPhone availability has expanded in the U.S.

Coming to No. 1
AT&T Inc. was the only U.S. carrier offering the iPhone when the first model came out in 2007. It lost its exclusive status in February 2011 when Verizon Wireless, the nation's top wireless carrier, started selling the iPhone.

Another national carrier
Sprint Nextel Corp., the No. 3 carrier, also got the iPhone, starting last October with Apple Inc.'s introduction of the iPhone 4S. It also sells the iPhone 4 with AT&T and Verizon Wireless.

Regional offering
C Spire Wireless, a small company that provides service in Mississippi and surrounding states, started selling the iPhone late last year. It bypassed larger carriers including T-Mobile USA and U.S. Cellular in getting the right to sell it. U.S. Cellular Corp. says it turned down the chance to sell the phone because it didn't want to spend a few hundred dollars per phone, as other carriers do, so customers can buy it at Apple's listed, subsidized price.

Cheaper iPhones
This spring, several small, regional cellphone companies began selling the iPhone at prices that undercut the big carriers. For instance, a basic 4S model was priced at $150 through those carriers, $49 less than what national carriers charge. Carriers making this cheaper offering include NTelos Wireless of Virginia; Appalachian Wireless of Kentucky; and Alaska Communications, Matanuska Telephone Association and GCI of Alaska.

No contracts
Leap Wireless International Inc., the parent of the Cricket cellphone service, and Open Mobile, which serves Puerto Rico, started selling the latest iPhone models on a prepaid, no-contract basis this year.

More now, less later
Virgin Mobile USA, one of Sprint's brands for prepaid, no-contract phone service, started selling the iPhone in June. It costs $549 for a basic model, higher than the $100 charged for Sprint-branded service. However, service will cost $30 a month and won't require a contract. Sprint charges $80 per month and requires a two-year contract. The Virgin Mobile customer can save nearly $800 over two years.

Leftovers
T-Mobile doesn't sell iPhones, but it will start advertising that AT&T iPhone owners who are out of contract can switch to T-Mobile. That had been possible, but iPhones had slower speeds on T-Mobile's networks. T-Mobile has reshuffled the frequencies on its network to let it match or even exceed AT&T's data speeds on iPhones. Initially, that will be noticeable only in a few spots scattered around in such cities as New York, Seattle, Las Vegas and Washington.