Like any mobile application, one of the characteristics of WhatsApp is its progressive update, in which it modifies and expands the functions of its messaging network. This causes that, as the specifications of the application increase, some phones (older ones) become obsolete and incompatible.
For that reason, in 2021 WhatsApp will stop working on different phone models, according to El Mundo. The company is working on different novelties (among them, the multi-device option) that will raise the operational demands of mobiles. WhatsApp, in its questions and answers section, has a list of the devices compatible with the use of the application.
Ice Cream Sandwich
WhatsApp clarifies that all Android with versions prior to 4.0.3 (known as Ice Cream Sandwich) are not compatible, so they will stop working. Or what is the same, devices with versions 2.3.7 or lower, will not be able to use the application.
Regarding the iPhone, all those who do not have iOS 9 will stop working. This implies that models 6, 5 and 4 (with all their versions, except for the iPhone 6S) will have to have iOS 9 installed to continue using WhatsApp. Older models are not supported.
Furthermore, WhatsApp informs that only “some phone models with KaiOS 2.5.1 or later operating system are supported, including JioPhone and JioPhone 2 devices”. Thus, those that do not meet these characteristics are also out of operation.