Many users reported that since the iOS version was upgraded to iOS 11/12, iPhone's visual voicemail always had problems and could not work well as before. Actually this is a common issue iPhone users meet, especially after iOS update. Sometimes, you find visual voicemail not available on iPhone without specific reason. Whatever it is, you're not alone. To help you out, this article will contribute to show possible solutions for you right now.
1. Reset Network Settings
2. Check and Update Carrier
3. Restart Your iPhone
For iPhone 7, you should press the Home button and the Volume Down button together until the Apple logo appears. For iPhone 8/X, press the Volume Up button and release it quickly; press the Volume Down button and release it in the same way; finally press and hole Power button until you see Apple logo.
4. Turn on/off Airplane Mode
5. Confirm/Reset Voicemail Passcode
6. Verify Whether Voicemail is Set Up on iPhone