Sprint, which has been losing subscribers, will spend $150 million to advertise the Instinct when it launches, compared with $30 million for a typical product introduction, according to David Owens, the company's director of devices.
Like the iPhone, the Instinct lacks a keypad and has just a few buttons. Most of the functions are accessed by touching the screen.
A few touch-screen phones appeared on the U.S. market last holiday season, after the iPhone's debut in June.
Verizon Wireless launched the LG Voyager, which has an exterior touch screen and folds out to reveal a non-touch screen paired with a keyboard. Sprint introduced the Touch by HTC, a slim pad with only a touch screen.
Both phones were hampered by the lack of software designed specifically for a touch screen. The Voyager dealt with that by adding a keyboard. The Touch grafted some touch-friendly features on to Microsoft Corp.'s Windows Mobile operating system, which is designed for smart phones that either lack a touch screen or are intended for use with a stylus. Some functions on the Touch are hard or impossible to use by tapping with the fingers alone.
The Instinct is based on a Samsung phone that's already available under different names, and with different software, in South Korea and Europe. Sprint commissioned its own software from European design house Icon Mobile.
"We took a more active part than we ever have" in a phone's development, Owens said. "This was designed from the ground up to be a touch-screen phone."
The software is based on Java, a commonly used programming language that should make it easy to develop applications for the phone.
The Instinct will have a few features the iPhone lacks. For one, it will be the first consumer phone in the U.S. to use EV-DO Rev. A, the fastest cellular broadband technology available on the Sprint and Verizon Wireless networks.
AT&T Inc. has phones that use a competing technology with equivalent speeds, but the iPhone is not one of them: It runs on a comparatively slow network, supplemented by Wi-Fi access.
The Instinct also contains a Global Positioning System chip, for location applications. The iPhone lacks one, but it can use cellular and Wi-Fi signals to determine an approximate position.
The Instinct's screen measures 3.1 inches diagonally, compared with the iPhone's 3.5 inches.
The Instinct won't be able to take input from more than one finger at a time: The iPhone's characteristic "pinch to zoom out, spread to zoom in" feature won't work. Sprint compensates for this by using the phone's motion sensor. In a demonstration of a prototype, tilting the phone while holding a button made a Web page scroll.