The mid-range Nokia Lumia 635 smartphone running Microsoft's latest Windows Phone 8.1 is headed to AT&T's network, where it will be available through the carrier's GoPhone pre-paid service.

Nokia unveiled its Lumia 635 handset a few months ago as one of the very first devices to come rocking Windows Phone 8.1 out of the box. We recently heard that the smartphone was making its way to T-Mobile in the U.S., but now more details have surfaced regarding the handset's availability on other carriers.

More specifically, AT&T has just announced that it will also be offering the Nokia Lumia 635. Come Friday, July 25, AT&T customers will be able to grab the Lumia 635 for $99 through AT&T's GoPhone pre-paid service. The carrier is not offering the smartphone on a post-paid basis, at least not for now. It's worth pointing out that the $99 price tag is promotional and applicable only for a limited time, as the Lumia 635 will cost $139.99 come Aug. 8. The device will also be available with AT&T Next for $5.84 per month or with AT&T Next 12 for $7 per month.

As a reminder, the Nokia Lumia 635 is a mid-range Windows Phone smartphone, packing decent specifications for its price tag. The handset sports a 4.5-inch FWVGA display, a quad-core Qualcomm Snapdragon 400 processor clocked at 1.2GHz, 512MB of RAM, and 8GB of internal storage capacity, expandable up to 128GB via microSD. Other specs of the Nokia Lumia 635 include a 5-megapixel rear camera and a 1,830 mAh battery.

In other words, the Lumia 635 is not a high-end smartphone with top-notch specs and features, but it will provide a good performance on a budget and will come with the very latest Windows Phone 8.1 OS on board. The new OS version boasts notable improvements over the previous iteration, bringing several neat features and improvements to the table. One of the most touted features of Windows Phone 8.1 is Cortana, Microsoft's new digital assistant and answer to Apple's Siri and Google Now, but there are plenty of other goodies in the cards as well.

To learn more about the Nokia Lumia 635's launch on AT&T's network, check out the carrier's announcement at this link.