Note: There is never a reason to give your sales pitch on voice mail. No one is there to say yes. Your objective is to make contact. Your objective is to provide enough information to create positive response.
2.) A gracious phone message is 30-45 seconds when talking to those we don’t know well. As George Washington said (yep, that George Washington), and I’m paraphrasing, “With men of business, be brief.” Be pleasant, and get right to the point. You’ll appear more confident and capable of handling the situation which merited the call.

“Good afternoon. You have reached the office of [your name]. I will be out of the office beginning on [date] and will be returning on [date]. Please leave a brief message with your contact information, and I’ll be sure to get back to you as soon as I return on [date]. If this is an emergency or you need to speak with someone before I return, please contact [name of colleague/supervisor], [their job title], at [their phone number].”
Use your regular, normal voice – not too excited, not too subdued. Talk how you’d talk on the phone with someone you like but who doesn’t make you nervous. Communicate ease without flippancy and importance without exuberance.