WhatsApp will not work on these phones starting December 31

Facebook-owned mobile messaging app WhatsApp will stop
working on a number of platforms from December 31, the
company has confirmed.
The messaging app will drop support for 'BlackBerry OS',
'BlackBerry 10', 'Windows Phone 8.0' and older platforms, from
December 31, 2017, according to an express.co.uk report
published on Monday.
"We will no longer actively develop for these platforms, some
features may stop functioning at any time," WhatsApp said.
"These platforms don't offer the kind of capabilities we need to
expand our app's features in the future. If you use one of these
affected mobile devices, we recommend upgrading to a newer
OS version, or to a newer Android running OS 4.0+, iPhone
running iOS 7+, or Windows Phone 8.1+ so that you can
continue using WhatsApp," the company added.
WhatsApp said that it will not work on 'Nokia S40' after
December 2018. Also, the app will stop functioning correctly on
Android OS version 2.3.7 and older, after February 1, 2020.