Sprint confirmed that it will offer unlimited data plans for the iPhone 4S starting Oct. 14, but it will also sell the iPhone 4 for $99.99 with the iOS 5 upgrade starting today.

The fact Sprint is selling the iPhone 4, and with the latest update of iOS software, came as a shock to many, but also at the lower price of $99.99 announced earlier by Apple.

Many assumed that Sprint would only sell the new iPhone 4S when Verizon Wireless and AT&T also put that device on sale Oct. 14.

"This is the first official announcement of which iPhone devices we will sell," a Sprint spokeswoman said today.

The iPhone 4S, announced Tuesday , will cost roughly the same at Sprint with a 99-cent premium compared to what Apple announced, starting at $199.99 for the 16GB model, then $299.99 for the 32 GB and $399.99 for the 64 GB version. Verizon Wireless today also announced pricing with the added 99-cent premium.

The iPhone 4 for existing users on AT&T and Verizon networks is supposed to be getting the iOS 5 update by Oct. 12, according to Apple officials on Tuesday, but Sprint's iPhone 4 for $99.99 will be available today with iOS 5, Sprint confirmed.

Both phones require activation on Sprint Everything plans with Any Mobile, Anytime for unlimited data, texting and calling to and from any mobile phone in the U.S. while on the Sprint network.

Those plans start at $69.99 a month plus a $10 Premium Data add-on charge. To get "truly unlimited calling data and text" on Sprint's Simply Everything Plan will cost a customer $99.99 a month plus the $10 Premium Data add-on charge, all while on Sprint's network, Sprint explained. The higher priced plan gives unlimited minutes of calling at anytime, while the $69.99 offers 450 minutes of calling at anytime.

Verizon Wireless separately announced it will begin online pre-orders for the IPhone 4S at 3:01 a.m. ET on Oct. 7, with availability on Oct. 14.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen or subscribe to Matt's RSS feed . His e-mail address is [email protected] .

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