Voicemail alert icons not clearing

[Daedriel]

The little icon for voicemail alert (two very small circles side by side connected on the bottom by a horizontal line) is persisting even after listening to and deleting all my voicemail messages. Powering the phone down does not eliminate it. This icon appears on my startup screen, on the phone app tile, etc., sometimes with a "1" beside it.

Any ideas how I can get rid of it? Tried the auto dialback and even that did not get rid of it. TIA.