AT&T just announced that the Microsoft Lumia 640 XL will go on sale on June 26. The 5.7-inch phablet will cost $250 off-contract or $0 down with AT&T Next.

Microsoft may still dominate the PC market with its desktop Windows OS, but the company hasn't been able to reproduce that success in the mobile world, where Apple's iOS and Google's Android reign supreme. The company is hoping to turn things around when it releases Windows 10 Mobile for smartphones and tablets in the fall.

While we're waiting for Microsoft to release Windows 10 Mobile and its new flagship Lumia 940, Microsoft has been steadily rolling out new Windows Phone 8.1-based smartphones, which will all be upgradeable to Windows 10 Mobile. The company's latest mid-range phablet, the Lumia 640 XL, has just been announced as an exclusive to AT&T.

"AT&T has proven to be the go-to carrier for Windows Phone devices. We are excited to add the Microsoft Lumia 640 XL to our industry leading Windows Phone lineup. Its large, high quality display makes it easy to do work and stay entertained when you're on the move. For less than $10 per month on AT&T Next 24 you will get a high performing smartphone at a very affordable price on the nation's most reliable 4G LTE network. What a great package," said Jeff Bradley, senior vice president, Device Marketing and Developer Services, AT&T Mobility.

The AT&T Microsoft Lumia 640 XL features a 5.7-inch 1280 by 720 Corning Gorilla Glass 3 ClearBlack display with a pixel density of 259 pixels per inch (ppi). The smartphone is powered by a 1.2 GHz quad-core Qualcomm Snapdragon 400 processor and 1 GB of RAM. It includes 8 GB of internal storage and a microSD expansion slot that will support up to 128 GB microSD cards.

The Lumia 640 XL's camera capabilities consist of a 13 megapixel rear camera with autofocus and 5 megapixel wide-angle front-facing shooter. It ships with Windows Phone 8.1 (Denim), which will be upgradeable to Windows 10 Mobile and it's packing a large 3,000 mAh battery, which will provide up to 25 hours of talk time.

The AT&T Microsoft Lumia 640 XL will be available in AT&T stores and online beginning on June 26. Qualified buyers can get the phablet for $0 down on AT&T's Next plans or $250 off-contract.