Google Pixel 4a 5G
Android 11.0
Select help topic
1 Find "Voicemail number"
Press the phone icon.
Press the menu icon.
Press Settings.
Press Voicemail.
Press Advanced Settings.
Press Setup.
Press Voicemail number.
2 Save voicemail number
Key in +447836121121 and press OK.
+447836121121
3 Return to the home screen
Slide your finger upwards starting from the bottom of the screen to return to the home screen.