You know, I have never given any thought, what so ever, to how my voicemail sounds to others, especially business associates. I am rather ashamed of how mine sounds.. now that I have read your article! I am going right now to change my to a more personable one. (I have the pre-recorded automated one that came with my phone, gggeeezzz)!
30. Hi, you’ve reached [your name] at [your company]. I’m unavailable right now on official duties. But if you leave your name and number and a brief message on why you are calling, I will call you back at the earliest opportunity.

“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].”
Voicemails need to maintain a professional consistency that’s aligned with the entity it’s representing. That said, the structure can vary depending on the situation. There’s no template set in stone. In fact, trite and generic should be off the table. The goal should be a balance of uniqueness and practicality.