If you use an old phone, or if you’ve never bothered to upgrade to the latest version of your phone’s operating system, it’s time to pay attention: WhatsApp might stop working on your phone soon. (Oh, and you really should upgrade your mobile OS anyway, you’re asking for a security breach if you don’t). Which Phones Will Stop Supporting WhatsApp? Estimates suggest more than 20 million handsets will be affected in total. Any phone running one of the following operating systems will no longer be supported.