Hey,
we have started rolling out a new software update for Lumia 640 & Lumia 640 XL. You can find the update instructions & update availability details from here: http://www.microsoft.com/en/mobile/support/software-update/wp8-software-update/
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.