Is extremely promising LT28at handset will be the first smartphone manufactured by Sony (already without Ericsson)? Bluetooth Special Interest Group has published a unknown family of specifications Xperia phone, codenamed LT28at.

Equipped with the Android smartphone is reportedly to have a screen size of 4.55 inches and a resolution of 720p and 4G capabilities.

The parts list also includes: 13-megapixel (rear camera and 720P-capable front-facing camera) cam with LED flash, video recording at 720p, two microphones, Bluetooth 2.1 and Wi-Fi operating in the 2.4 and 5GHz frequencies.

Dual-band 802.11 N Wi-Fi is supported, as are LTE, HSPA, and TD-SCDMA — which ensures that LT28AT play nicely with China’s cellular networks.

It’s also known that the Sony LT28AT is heading for the U.S., where it’ll ride on AT&T’s network. Horsepower isn’t mentioned in the Bluetooth SIG posting, but some sources are reporting that it’ll run a dual-core chip clocked at 1.5GHz — just like the Nozomi LT26i.

At this point, no images have leaked.

More at Xperia Blog