(Microsoft has said the 640 can be upgraded to Windows 10 Mobile later this year.) Windows Phone 8.1 is a robust ... buildup to Windows 10. The Lumia 640 and 640 XL are worthy update to the ...

4G bands 1, 3, 7, 8, 20 1, 2, 3, 4, 5, 7, 8, 12, 17, 20, 28, 38, 40 Speed HSPA 42.2/5.76 Mbps, LTE Cat4 150/50 Mbps HSPA 42.2/5.76 Mbps, LTE Cat4 150/50 Mbps ...