Currently powered by the Series 30+ operating system, Nokia feature phones have been declining in sales. While sales have been declining, there seems to still be some juice to squeeze out of Nokia, shipping over 400 million units in 2015.
Back in 2013, Microsoft acquired the feature phone company for a reported $7.2 billion. While the PC giant no longer owns Nokia, the company will continue to develop Windows 10 Mobile to support the Lumia phones.