Imagine listening to a voicemail from a salesperson who is just so excited about the message that their tone is now unnaturally high-pitched and energetic. Today, people aren’t fooled by that, and in trying to make the message more meaningful, this approach actually makes it less meaningful.
“Keep your voicemail messages short, sweet, and snappy," advises Will Craig, Managing Director of LeaseFetcher. "Don’t try and go into the nitty gritty details of the discussion you’d like to have with them—save that for your actual chat. Alternatively, don’t leave them in the dark about what you want to talk about either. A simple 20-second voicemail letting them know the nature of your query will suffice."

And that's the reason that most people leave garbled and rushed messages, because they take about two seconds to adjust to the fact that they've got through to an answering service and then with Mary Mitchell's message they have maybe a second or two to compose a short and concise message... which just isn't enough time for most people.
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.