Messaging service WhatsApp will no longer work on millions of smartphones from 1 February.
The Facebook-owned app stopped supporting a number of devices on December 31 and on February 1 it will declare lots more iOS and Android handsets out of date.
Just a month after WhatsApp ended support for some of the older smart mobile models, the Facebook-owned instant messaging App has now added more devices to the list of the phones that won't be able to run WhatsApp.
WhatsApp said the move was necessary in order to protect the security of its users.
Smartphones using Android 2.3.7 and older, and iPhone iOS 8 or older, are those affected by the update.
The operating systems that WhatsApp is dropping support for are legacy operating systems, which are no longer updated or installed on new devices.
Most users will simply be able to update their operating systems in order to continue using the messaging service.
However, certain devices, such as iPhone 4s, which only support iOS 7, will no longer be compatible with the app.