Dingtone needs to stay in the background to receive incoming calls and messages. Please do not terminate the Dingtone app after you close it. Some third-party battery-saving/memory-saving apps may terminate Dingtone. Please add Dingtone to their whitelist.
Please also make sure notification is enabled for Dingtone on Android phone. You can enable notification for Dingtone on Android phone by conforming to the following tapping: “Settings” >> “Notifications” and then enable Dingtone. Different Android phones may have different setting steps.