The Microsoft Lumia 640 and Microsoft Lumia 640 XL are Windows Phone smartphones developed by Microsoft Mobile. Both phones were announced on March 2, 2015, and are the successors to the Nokia Lumia 630 series and the Lumia 1320, respectively. The phones are primarily aimed at developing markets, although they are also available in developed markets as lower-cost options compared to other phones in their classes. The two devices became available in the US and most other markets in June 2015.

Windows 10 Mobile was a mobile operating system developed by Microsoft. First released in 2015, it is a successor to Windows Phone 8.1, but was marketed by Microsoft as being an edition of its PC operating system Windows 10.