Your voicemail should be very specific. It should be short and urgent. Use word's like "need", "should", "must" , or "have to" to create a sense of urgency. For example, say something like, "We need to discuss..." or "We should talk about..."
Creating funny voicemail messages that are fun for your callers to listen to can be quite entertaining for you too. Instead of leaving a standard, boring voicemail greeting in place, you can use a little creativity that makes callers chuckle or laugh out loud. An easy way to come up with ideas is to do a play on popular TV shows, parody a government agency, or give voice to a machine that has come to life and is expressing its unique personality. A private voicemail box enables a person to receive telephone messages when the phone cannot be answered.

Being personable is key in having your caller look forward to receiving your callback. To do this, use different intonations in your voice to convey enthusiasm.
No19: I can't come to the phone right now because I'm down in the basement printing up a fresh new batch of twenty dollar bills. If you need any money, or if you just want to check out my handiwork, please leave your name, number, and how much cash you need after the tone. If you're from the Department of the Treasury, please ignore this message.