Sony Xperia XZ3
It's not possible to check my voicemail
Solution 5 of 6: The voicemail number isn't saved on your phone
You can save your voicemail number making it easy to call and listen to your voice messages.
Press Phone.
Press the menu icon.
Press Settings.
Press Voicemail.
Press Advanced Settings.
Press Voicemail settings.
Press Voicemail number.
Key in +447953222222 and press OK.
Press the Home key to return to the home screen.