Have Energy in Your Voice—When you record your voicemail greeting, make a positive impression. Speak as though you are enjoying a successful life. People are instinctively drawn to people with positive attitudes. If you sound like you just woke up, you will likely make a negative impression.
Check out my guide on how to start your business right with tons of useful tips I learned by successfully starting, building, and selling multiple companies.

You’ll want to have your office hours in the voicemail so that cleaning customers know when they can connect with you. You don’t have to always be available during all of those times, it’s just the possibility you’ll actually pick up your phone or will be able to give them a call back during those hours. Adding in office hours makes your business sound much more professional. It’s the sign of a more established, well-run company to have business or office hours.
“People often assume the voice mail lives on the phone when in fact it lives in the carrier's server. Verizon Wireless spokesman Paul Macchia said the company has a deal with CBW Productions that allows customers to save greetings or voice mails to CD, cassette, or MP3.”