29. Hi, you’ve reached [your name] at [your company]. Please send me an email at [email address] if this is urgent, and I’ll get in contact with you as soon as possible. If this is not urgent, please leave me a brief message about the reason you are calling with your contact information and I’ll get back to you in the next 24 hours. Have a great day.
Users often don’t invest enough time into their messages, resulting in incomplete, unprofessional, or otherwise under-whelming greetings. Sure, crafting a greeting doesn’t sound all that complicated; however, there are a number of pitfalls users can fall into—i.e. informality, terseness, sincerity, lack of direction, and more. While none of these sound too catastrophic, they are often interrelated. As such, they tend to worsen any problem. For example, humor can cause informality, worsen ambiguity, and weaken sincerity. That being said, users should strive to avoid ALL these pitfalls.

The unavailable message is the standard greeting callers hear when they reach your voicemail box. It is the greeting that you can use consistently throughout the work year.
There is no definitive answer here, but you should include one of the two at the beginning of your message based on what makes the most sense.