The scenario is that they want to send a private or confidential voicemail and ensure that the recipient can't forward that message to certain people or people not on some approved list. Apparently their former voicemail was able to accomplish this task.

My thought on this is that since Unity is beholden to Exchange, the answer is
Due to the COVID-19 pandemic, I am currently operating remotely and am not checking this voicemail. Please email me at [insert your email address].

You have reached (your business name). We may be on the line with another caller at the moment or away from our desk. Please leave your name, phone number, and a brief message and we'll return your call promptly
“Hi, you’ve reached [your name]. I’m away from[date] to [date]. If you need help with [X] before then, please contact [name] at [phone number]. Everyone else, please leave your name and number and I’ll return your call when I return. Thanks and have a great day.” “Hello, you’ve reached [your name]. I’m currently [exploring Asia, hiking through the jungle in Costa Rica, hanging out on the beach in Bermuda] — or more likely, [recovering from extreme jet lag, googling ‘Are red spiders poisonous,’ or looking for SPF 150 sunscreen] and won’t be back in the office until [date]. Leave your contact info and reason for calling and I’ll get in touch then.” “Hey there, this is [your name] from [your company]. I’m out of the office until [date]. In the meantime, please direct your inquiries to [coworker’s name] at [email address]. [He, she] can also be reached at [phone number]. Thank you.”