The iPhone 4S was introduced at a product event, led by new Apple CEO Tim Cook, at the company's headquarters in Cupertino, Calif.
The phones will feature longer battery life, an enhanced 8-megapixel camera and a faster processor, which helps run smoother, more realistic action games. It's also a "world phone," which means that Verizon iPhones will be useable overseas, just as AT&T iPhones already are.
Another new feature included in the iPhone 4S is a "personal assistant" application called Siri, which responds to spoken questions and commands. It's an advanced version of speech-recognition apps found on other phones.
The new iPhone also comes with new mobile software, iOS 5, that includes such features as the ability to sync content wirelessly, without having to plug the device to a Mac or Windows machine.
Apple also unveiled software that can send greeting cards through the postal system for $2.99 each.
The new phone will be available in black or white. It will cost $199 for a 16 gigabyte-version, $299 for 32 GB and $399 for 64 GB - all with a two-year service contract requirement. It will now be available through Sprint Nextel Corp., besides the existing carriers, AT&T Inc. and Verizon Wireless.
The iPhone 4 will now cost $99 for 8 GB and the iPhone 3GS will be given away for free with 8 GB -- both also require a two-year service contract.
Pre-orders will begin Friday with availability on Oct. 14.
Over the past few months, there had been speculation about a more radical upgrade of the phone, an "iPhone 5." The no-show leaves room for more speculation that Apple will reveal a new model in less than a year, perhaps one equipped to take advantage of Verizon's and AT&T's new high-speed data networks.
IOS 5 will also be available on Oct. 12 for existing devices - the iPhone 4 and 3GS, both iPad models and later versions of the iPod Touch.
Apple's new iCloud service, which will store content such as music, documents, apps and photos on Apple's servers and let people access them wirelessly on numerous devices, will also launch on Oct. 12.
Apple also unveiled a new line of iPods, including a Nano model with a multi-touch display that promises to be easier to navigate. Apple did not discuss its Classic model, which many people had speculated the company might discontinue.
This is Apple's first major product announcement in years without Steve Jobs presiding. Jobs resigned from his CEO post in August because of health problems.
The Associated Press contributed to this report.