As we inch closer to 2017, millions of smartphone users will need to upgrade their handsets if they want to continue using WhatsApp
The messaging app - which boasts over one billion users worldwide - is on the verge of ending support for a number of older smartphone models
In a blog post, the Facebook-owned app said it will be phasing out compatibility with older phones.
"While these mobile devices have been an important part of our story, they don't offer the kind of capabilities we need to expand our app's features in the future," Whatsapp wrote on its website.
The company proceeded to say technology has changed dramatically since its inception, which led to its decision to drop support for ageing mobile platforms
But anniversary dates are also an opportunity to look back. When we started WhatsApp in 2009, people's use of mobile devices looked very different from today.
Mobile operating systems offered by Google, Apple and Microsoft - which account for 99.5 percent of sales today - were on less than 25 percent of mobile devices sold at the time.
As we look ahead to our next seven years, we want to focus our efforts on the mobile platforms the vast majority of people use.
Will you be affected by the cutoff? Here's what you need to know:
iPhone: The app will stop working on iPhone 3GS at the end of this year. It will also cease to function any iPhone running iOS 6, so any phone which hasn't been updated to a later operating system will lose WhatsApp.
Android: WhatsApp will cease to function on any Android tablet or phone running Android 2.1 or 2.2. This covers devices released between May 2010 and November 2011 from many different manufacturers.
Windows: Anyone still using Windows Phone 7 will not be able to use WhatsApp anymore.
WhatsApp was planning to drop support for BlackBerry OS, BlackBerry 10, Nokia S40 and Nokia Symbian S60 at the same time as the above operating systems, but it had a change of heart
The support period for these devices has been extended to June 2017.