Looks like the RingCentral Phone app for Android has been removed from the PlayStore. RingCentral still has links to download on their website, but the URL isn't returning anything from Google. Is this planned or a hiccup? Phones with the software previously installed are OK, but new phones can't download the app.
https://support.ringcentral.com/download.html?language=en_US
https://play.google.com/store/apps/details?id=com.ringcentral.android