There are several Android and iOS phones which will not be ready to run the app because the company will withdraw support for older versions of OS from next year.
According to the knowledge on the WhatsApp Messenger FAQ section, WhatsApp Messenger will only be compatible with phones running the Android 4.0.3 OS or newer also as iPhones running on iOS 9 and newer.
All iPhone models up to the iPhone 4 will lose support for the messaging platform next few days. The iPhone models include the iPhone 4S, the iPhone 5, the iPhone 5S, the iPhone 6, iPhone 6S.
For Android, devices including HTC Desire, Motorola Droid Razr, LG Optimus Black, Samsung Galaxy S2 will lose WhatsApp support as 2020 ends.
The instant whatsapp messaging platform will keep the app running for select phones with Kai OS 2.5.1 OS or newer, including JioPhone and JioPhone 2.
To check which OS an iPhone is over to the Settings menu, then to option, Software users see the OS running that particular iPhone.
Android users can head to Settings, then About Phone which Android version their smartphone is running on.