When you have new voicemail, the Phone tab in the Skype for Business main window displays the number of your messages. See Contact Card opens the caller's contact card, which lists their phone number, email address, office location, and so on. Open Item in Outlook provides more information about the call.
Random facts could include their favorite movie, vacation spot, candy, or television show. Regardless of what you choose, it will surprise your caller and more than likely make them leave a message if they were considering hanging up.

I have a confession to make: I haven't recorded a new voicemail greeting in nearly a decade. Since then, I've (hopefully) become more articulate, poised, and self-assured. But hear my voicemail recording, and you'd think I was still new to the work world, a little unsure of myself — and probably not an authority.
That’s why it’s critical that each customer interaction with your business is consistent, positive, and represents the values and personality of your company. This includes your storefront, website, social media presence, emails, and every interaction you have with your customers, both online and in-person.