Apple ipod

How to reset a password for voicemail on the iPhone with the knowledge?

My iPhone says I have an e-mail password voice, but I do not agree to one. Can anyone help me find a way to restore or delete it?

When set up visual voicemail, I think must set a password. If you call customer service at 611 or 1800-331-0500. Option 3? Voice messaging is, and there is an automatic option to reset the password voicemail.

iPhone 4 (voicemail password)