Do I need a voicemail passcode
Can I disable my voicemail code?
iPhone 11, iOS 16
Question marked as
No, you don't need a voicemail code / pin.
The voicemail settings are controlled by your carrier, so contact your carrier, to have the voicemail code / pin removed.
I don't use a voicemail code / pin.
But don't let other people have access to your iPhone or other Apple device, change the device passcode and never share it with others.
If you want to change, see Change your Passcode -> Use a passcode with your iPhone, iPad, or iPod touch - Apple Support