If you have suddenly started seeing small dot (badge) above Zoiper, or circle with the number "1" in it, this means that you have device with Android above version 8.0. 

This dot appears when the "Registration channel" is enabled. You can find detailed information exactly what it is on the article here.

To disable it simply follow the steps below:

• Go to Android "Settings"=>"Applications"=>"Zoiper"=>"Notifications"
• Select "registration channel" and disable "Show notification dot"

Note: On some devices the exact place where you can find this option might be slightly different, if you cannot find it, please refer to the manual of your device. 

You may also not see the notification dots at all on some devices (e.g. Huawei with Android 9).