This BBC Blog states:-

" From today, the BBC Sounds app will begin to be made available to download on international app stores, available for devices capable of running iOS 11, Android 5 or Amazon OS 5 or above. People who currently use the iPlayer Radio app outside the UK will now begin seeing messages encouraging them to download the BBC Sounds app and switch over. At some point in the near future, the iPlayer Radio app will stop working, and listeners will need to get the BBC Sounds app to continue listening. "