1) Description: This is necessary to properly stop the silent mode by capturing the incoming / outgoing call origination and exit points of the phone call, since if the silence mode is turned on, no sound is heard.
2) Required: You can use the app normally without having to grant this permission on Android 6.0 or higher devices. At this time, you don't have the function described above. Devices under Android 6.0 do not have the ability to selectively grant permissions, so this permission is automatically granted.
* SilentMode does not require Internet permission. In other words, users' data or information is not transmitted to the outside using network.