T-Mobile USA just announced it will exclusively offer the waterproof Sony Xperia Z flagship, as well as the Nokia Lumia 925, starting on July 17.

In other words, although the carrier's bestsellers are the iPhone and Samsung Galaxy smartphones, T-Mobile wants to expand its "un-carrier" plans to suit more tastes and budgets.

"T-Mobile will be the exclusive U.S. wireless company to offer Sony's flagship water-resistant Android-powered smartphone to customers this summer," the carrier boasts in the press release announcing its "boldest moves yet as America's un-carrier."

The Sony Xperia Z will land on T-Mobile's network with a $99.99 price tag up front, followed by 24 equal monthly payments of $20. Starting on July 16 interested buyers will be able to pre-order the smartphone from T-Mobile's website and receive a free Sony Wireless Bluetooth Speaker as a gift with the purchase of the handset. This bundle will be available "while supplies last."

Meanwhile, the Sony Xperia Z is already available for purchase at 38 U.S. Sony Store locations or online from Sony's website. Customers who purchase their device from Sony will also receive the free Sony speaker while supplies last.

Sony's latest flagship smartphone is waterproof and dustproof and boasts a 5-inch Full HD (1080p) display, a quad-core processor clocked at 1.5GHz, 2GB of RAM, LTE, a 13-megapixel rear camera and a 2-megapixel front-facing shooter. The Sony Xperia Z comes with Android 4.1.2 Jelly Bean out of the box, 16GB of internal storage expandable via micro SD, and a 2,330 mAh battery.

The Nokia Lumia 925 is the cheapest among the two new handsets to join the carrier's lineup. T-Mobile will start selling the Lumia 925 next week for a down payment of $49.99, followed by 24 monthly payments of $20.

Nokia's latest Windows Phone 8 (WP8) flagship smartphone has been available in Europe since last month, and now it's finally making its way to the U.S. The Nokia Lumia 925 sports a 4.5-inch PureMotion HD+ ClearBlack display, an aluminum body, a dual-core processor clocked at 1.5GHz, an 8-megapixel rear camera and a 1.3-megapixel front camera. The handset also packs 1GB of RAM, 16GB of internal storage, a 2,000 mAh battery and LTE. The Nokia Lumia 925 will launch as T-Mobile's first 4G LTE Windows Phone smartphone.

Lastly, T-Mobile also announced that it will roll out a software update to the Samsung Galaxy Tab 2 10.1 in the coming weeks, making the slate LTE-compatible.