The 640 XL and its tweaked firmware...
From the Microsoft forum post:
We have started rolling out a new software update for Lumia 640 & Lumia 640 XL:
Latest software release for Nokia Lumia 640 is Lumia Denim (02177.00000.15184.36xxx/8.10.15148.160):
- Voice over LTE support enabled for selected operators.
- Native Wi-Fi calling support enabled for EE UK and T-Mobile USA.
- Additional improvements to stability, audio quality, Wi-Fi and cellular connectivity, national roaming, and more.
Latest software release for Nokia Lumia 640 XL is Lumia Denim (02177.00000.15184.36xxx/8.10.15148.160):
- Voice over LTE support enabled for selected operators.
- Native Wi-Fi calling support enabled for EE UK.
- Additional improvements to stability, audio quality, Wi-Fi and cellular connectivity, national roaming, and more.
Good to know, in these days of flashier smartphone features, that telephony (even if data assisted) is still being improved! See also our full reviews of the Lumia 640 XL and Lumia 640.
As mentioned above, the same version of Windows Phone (8.10.15148.160) is also rolling out to Lumia 830 and 735 units across the world. We'd been led to believe by Microsoft that some USA units would get the Update 2 firmware for legal reasons (remote wiping is becoming required by the FCC), but it's good to see this upgraded OS variant making it across the pond. See our coverage here of what's actually new, over and above 8.1 Update 1.