I can't check my voicemail on my Samsung Galaxy S9 Android 8.0
Cause 3 of 5: You're trying to check your voice messages when abroad
The default voicemail number can only be used if you're calling form your home network.
Solution: Call +447836121121 and key in your 4-digit PIN to check your voice messages when abroad. Please note that you need to set a PIN before you can check your voice messages when abroad.