Voicemail icon shows one voicemail but tapping reveals no voicemails on iPhone

The synchronization between a phone’s VM copy and your carrier’s VM master — and the “toggling” of any VM Waiting Indicator — has ALWAYS been a challenge for carriers.

Occasionally it still gets out of sync.

Nothing to worry about.

You can easily check what VMs are actually “on” your carrier’s VM server by dialing-in directly to your carrier’s VM access number.

People do hang up when they are confronted with voicemail since they wanted to talk to you not a piece of hardware and that will give you the indicator on you iPhone that there is a voicemail waiting for your retrieval.