A relatively unprofessional one — like mine, for instance — does the opposite: It encourages prospects, recruiters, and potential connections to run in the other direction.
Enterprise level organizations can use professional voice mail prompts to establish brand and consistency. Smaller organizations and even one person firms can represent themselves as a professional and established organization that understands how to present themselves to the business world and their potential client base.

With that said, we thought it would be a good idea to provide you with a few examples of voicemail greetings. As you read through these, keep in mind that the effectiveness of your voicemail greeting is one-quarter what you say, and three-quarters how you say it.
Hello! Thanks for calling [LinkedPhone’s Customer Success Team]. We are currently helping other customers achieve their goals and want to do the same for you! Please leave a message with your name, number, and a brief description of how we can serve you. We promise to return your call [before close of business today]. In the interim, you can also check out our website at [linkedphone.com] for helpful answers to our most common requests. Thank you.