I know my apple id and password but my new iphone 5 is asking me for my "voicemail password" and I dont know what that is and how can I disable this request?

The voicemail password is independent from Apple/your iPhone and is related to your service provider. If you already set a password for your voice mailbox, you would need to input it in order to access your voice messages associated with your cell-phone plan. If you forgot your voice-mail password or did not set one, I'd advise you to simply call your cell-service provider support which should quickly resolve the issue.