Hello and good evening, @Dutta. 

Check network connection: Make sure your iPhone has a stable mobile connection, as voicemail services rely on the cellular network.

Toggle Airplane Mode: Sometimes, enabling Airplane Mode for a few seconds and then disabling it can help reset the connection to the cellular network.

Reset Voicemail settings: Go to "Settings" > "Phone" > "Voicemail" and check if your voicemail is set up correctly. You can also reset the voicemail settings and re-enter the number if necessary.

Manually enter voicemail number: In some cases, you may need to manually configure the voicemail number. You can do this under "Settings" > "Phone" > "Voicemail." Look for an option to add or edit the voicemail number and enter the correct number.

Restart your iPhone: A simple restart can often help resolve connection issues.

Update carrier settings: Sometimes, updates from your carrier may fix the problem. Go to "Settings" > "General" > "About" and check if an update is available.

Hello @Dutta,

thank you for letting us know. 
I'm happy to read that your voicemail is working properly again.

Feel free to write us again, if there's anything else we may help you with.

Have a nice evening.

Kind regards

Malte