Some of the phone models that will be without WhatsApp next month are:
In the case of iOS, which is also affected but to a much lesser extent, the limit is set at iOS 10 or higher. WhatsApp’s help center is even more specific and lists Android 4.1 or higher as a requirement to install or update the application on Android. WhatsApp ends support for many Android phones in November It is the estimated release date for the new version of WhatsApp. So any device with a version equal or lower will lose any possibility of updating from next November 1.
For now, WhatsApp is available for devices that have Android 4.0.4 or later.
