Your voicemail needs to have relevant information such as your name, who the prospects are connecting to, the department you work in, why your not available to assist your prospects, when you will call them and related information, this is what the prospects would prefer hearing instead of dragging the voicemail messages speaking about your brand and more.
Made famous by George Costanza as you can see the clip here, the answering machine song may seem like a good idea. It's out of the box, unexpected, and definitely a novelty, but unless you're in the music business, it's probably not a good idea. You'll definitely irritate your mother (or anyone else important who calls you frequently) and you won't make a good first impression with your message.

When you want callers to leave a message, make sure your voicemail greeting indicates that. Be sure to keep your greeting short and direct, and include the info you want to capture.
You could add the words "After-Hours Service" or "After-Hours Line" after the company's name. That way there's no concern over whether it is indeed a number that reaches a real person who will return their call during non-business hours. It's a way to let them know they're on the right track. If that makes sense. :)