Messaging app WhatsApp has stopped working on a range of dated smartphones today, the company has confirmed.
From December 31, WhatsApp, owned by Facebook, will no longer work on Microsoft's Windows Phone and all smartphones running on Windows Mobile software as the company no longer develops for Windows mobile platforms.
Facebook said users of Microsoft operating systems had not been able to create new Whatsapp accounts since earlier this year, after Microsoft announced it intends to kill off its phone software.
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Microsoft has urged smartphone users still using its operating systems to switch to an iPhone or Android by January.
WhatsApp, which launched in 2009, has also confirmed it would remove some support for some older Apple and Android devices in 2020.
Android versions 2.3.7 and older, and iOS 8 and older will lose support for the messaging service on February 1, Daily Mail reports.
Each year WhatsApp removes support for older devices it says do not "offer the kind of capabilities we need to expand our app's features in the future".
"'This was a tough decision but the right one to give people better ways to keep in touch with friends, family and loved ones," the messenger service said.
Some support for older phone using Windows operating systems was removed at the beginning of 2018, along with support for BlackBerry devices.
Facebook stopped developing its Facebook, Messenger and Instagram apps for Windows Phones in April.
Apple says only 7 per cent of devices are running on a version of its operating system older than its latest iOS 12, released in 2018.
WhatsApp will continue to support devices running on Android 4.0.3 and onwards, and iPhones running on iOS 9 and onwards.