Microsoft first showed its latest major update for Windows Phone earlier this year. After an open developer beta which lasted for a couple of months the company finally started rolling out the update a couple of weeks ago. Folks with carrier devices had to wait a bit longer to receive the update and today the wait ends for AT&T Lumia 520 and Lumia 925 owners. The carrier has finally released Windows Phone 8.1 update for both smartphones. Windows Phone 8.1 is one of the biggest update that Microsoft has made for its mobile platform. It is compatible with any device that’s running Windows Phone 8.0. AT&T has previously rolled out the same update for the Lumia 1520, one of the high-end models in the Lumia family.