Apple iPhone pre-orders: What carriers are offering

Apple enthusiasts are lining up online to secure the release of the iPhone 6, which officially goes on sale next week.

The new iPhones—which are bigger and faster, with a better camera and a longer battery life—went on sale pre-order Friday morning at 3 a.m. EST, and several models already have sold out or will see substantial delays.

Analysts expect sales to hit records or near records.

"I think if you look at the market that they're going after, those Samsung, the bigger-screen Samsung, it just has a fundamentally different feel to it. And ultimately I think the thinness and the battery life, the combination of all there of those, are really going to power this product cycle," says Gene Munster of Piper Jaffray.

The battle for iPhone customers spans the nation's biggest retailers, and an aggressive incentive battle is being waged among the country's leading wireless carriers.

Wal-Mart will sell the iPhone 6 starting at $179 on a two-year contract. The iPhone 6 Plus will sell for $279, saving $20.

Competition among carriers is intense. Some are offering deals on the new phones, others are offering trade-ins for older iPhone models to attract customers.

Verizon is offering an iPhone 6 for free for customers who trade in older models, and sign up for a new two-year contract. Customers get a $200 gift card that can be applied to the 16-gigabyte version of the phone.

For its part, starting Friday, AT&T is letting customers get up to $300 when they trade in their old iPhones, credit they can use toward buying a new iPhone, or pay off a bill.

T-Mobile promises to offer customers the best price when doing a trade-in. If a customer can find a better trade-in offer from a major carrier, T-Mobile says it will beat the offer, give them the difference back, and top it off with another $50.

Not be outdone, Sprint is offering what it calls the "iPhone for life" plan. For $70 a month, users lease the iPhone 6 and then upgrade to a new version every two years.

The new phones go on sale Sept. 19, though pre-orders started Friday, and have already sold out. Analysts at RBC say Apple could sell 10 million iPhones that weekend, a new record and one million more than when the 5S and 5C were launched last year.