Dallas - AT&T became the first U.S. carrier to announce an availability date for one of HTC's new One series of Android 4.0 smartphones, which were unveiled at February's Mobile World Congress.

AT&T plans May 6 availability of the HTC One X at $199.

The unibody phone, equipped with LTE and HSPA+ 4G technology, is AT&T's first smartphone to launch with Android 4.0, first AT&T smartphone with Beats by Dr. Dre Audio technology, and first AT&T smartphone with HTC's new Sense 4 user interface.

The One X was among a trio of One-series phones unveiled earlier this year for U.S. and foreign carriers as part of HTC's effort to reinvigorate sales, which have declined in recent months on a year-over-year basis.

The trio includes the HTC One S, due from T-Mobile sometime in the spring, and the One V, which will be available from C-Spire, Cincinnati Bell, MetroPCS, U.S. Cellular and Virgin Mobile. Their prices and availability dates haven't been announced.

AT&T's One X features a Qualcomm dual-core 1.5Hz processor, 4.7-inch 720p Super LCD display, and 8-megapixel camera with 1080p video capture.

All three One-series phones apply Beats audio technology across all music sources, not just stored music. All three also feature a new Music Hub that lets users store music, music applications and streaming-music apps in one onscreen location.

All also have HTC ImageSense, a new suite of camera and imaging features that include multiple features not previously offered by HTC. These include Superfast Capture, which reduces the time to take a picture to 0.7 seconds. Fast 0.2-second autofocus lets users take continuous shots by holding the shutter button.

The camera suite also includes f/2.0 lens on the HTC One X and HTC One S to capture 40 percent more light than f/2.4 lenses available on other smartphones.

It has Concurrent Video/Still Capture, letting users shoot video and capture a photo at the same time, and high dynamic range (HDR) technology, which improves contrast in captured photos. HDR takes multiple photos of a subject in rapid succession, each with a different exposure level, then layers the photos to create a single photo that combines the best parts of each image to deliver a more accurate range of light.

The suite also introduces autoburst, a feature that automatically take a burst of shots of a subject if the subject moves while the user is pressing the shutter button.

The top-end One X and One S feature 8-megapixel camera with 1080p video capture, while the One V features a 5-megapixel camera with 720p video capture.

The HTC One S features a contoured 4.3-inch qHD AMOLED touchscreen, dual-core 1.5Hz Qualcomm processor, 0.3-inch depth to make it HTC's thinnest phone to date, 4G HSPA+ 42Mbps technology, and Qualcomm dual-core 1.5GHz processor. It will also be T-Mobile's thinnest phone to date.

The One V, promoted as offering "broad appeal," features a 3.7-inch screen.