CALLert allows you to configure select contacts such that when they call you, the phone ringtone is played even when in silent mode (at zero volume). This app can help you to. Tell someone to wake you up and keep the phone in silent mode, so only that person's call will make the phone ring, and you won't be disturbed by unwanted phone calls.
This application is totally safe for downloading. Gautham S Yaji is the creator of the app that can be found in the Communication category. The average user rating of CALLert is 3.
Over 1K users downloaded and set up this application and its latest release was on May 27, 2018. You can download the installer of CALLert 3.1 for free and have a look at users' reviews on Droid Informer. The app works fine on Android 4.0.3 and above.
Some users have noticed that the strong side of the app is a simple user interface.