There is a great news of Microsoft Lumia 640 users, the company has declared that the Lumia 640 as well as its larger variant Lumia 640 XL will be first devices to experience the upcoming Windows 10 for phones.
In terms of specs, the Lumia 640 is equipped with a 5 inch 720p display with a density of 294ppi, and is powered by a Snapdragon 400 SoC with quad-core 1.2GHz processor. It packs 1GB of RAM, 8GB of internal memory (expandable up to 128GB via microSD slot), an 8 megapixel rear snapper, 0.9 megapixel front shooter, and a 2,500 mAh battery.
The Microsoft Lumia 640 and the Lumia 640 XL were launched in India last month, and are now accessible in the UK too. The Lumia 640 has also made a brief appearance on official Microsoft site in the U.S., giving an idea for associated carrier and pricing.