Whatsapp, why the app doesn't work on old smartphones - Software and Apps. It is active starting from Android 5.0 and iOS12 operating systems (ANSA) WhatsApp is not available on older smartphones for periodic updates relating to compatibility with the operating system.
The list of older cell phones that no longer support WhatsApp includes various models from brands such as Samsung, LG, Huawei, Sony, Lenovo, ZTE, and even some iPhone models. These are devices that mostly date back seven to 10 years ago.