Microsoft this morning began pushing out a new OS and firmware update for some Lumia 640 and Lumia 640 XL devices. Even more interesting, this update brings some new features including one for the yet-unreleased Lumia 640 on T-Mobile.

Unlocked and regional variants of the both devices should begin to see an update waiting for them on Microsoft's servers. The OS gets bumped to version 15148, which is a rather large jump from the current 15127 found on many Lumia 640 and Lumia 640 XLs. The firmware is updated to version 15184.36xxx.

Here are the changes for the updates on both phones.

Lumia 640 and Lumia 640 XL OS 15148 Changelog

Voice over LTE support enabled for selected operators.

Native Wi-Fi calling support enabled for EE UK and T-Mobile USA (Lumia 640 Only).

Additional improvements to stability, audio quality, Wi-Fi and cellular connectivity, national roaming, and more.

The mention of T-Mobile for the Lumia 640 is certainly attention-grabbing. Marketing for that device has been spotted in Walmart, but there has been no solid lead on when it launches.

The addition of Voice over LTE (VoLTE) is certainly a big deal for many as well. The new standard helps deliver higher quality audio, and it is commonly referred to as 'HD Voice' by many carriers. Needless to say, it is exciting to see that feature enabled on both of these new Lumias.

To check for the update, head into Settings > Phone Update > Check for Update. Reports from India and other regions have confirmed the rollout has begun, although here in the US our Cricket Lumia 640 has not received the update, so your mileage may vary.

Source: Microsoft; Thanks, Melwin, and Yahia, for the tips