Your phone system can be a powerful marketing tool for your business, and that includes your voicemail greeting. If you want to utilize this opportunity to throw in a quick humblebrag and keep callers informed of your awards and accolades, there are a few best practices, you should follow. First, keep the self-promotion brief and appropriately placed within your voicemail message. Don’t promote yourself and your products/services in the same greeting, and finally, only include current achievements in your business voicemail greeting.
In certain situations, it’s a good idea to let a call go to voicemail. If you’re in a loud area, unable to spend 10-15 minutes talking, or are otherwise distracted, don’t answer. Recruiters who cold-call candidates will understand that you’re simply unavailable – but make sure to return calls in a timely manner. If possible, call back during regular business hours.

And then there's everybody's favorite the "butt dial message." You see a missed call from that person and the voicemail icon. You think to yourself, "wow if they called me and left a message it must be important." Utter disappointment and frustration sink in when there is nothing but silence on the message.
24. Hello, you’ve reached [business name]. Every call is important to us, so please leave a brief message that includes your name and phone number so a member of our customer success team can call you back as quickly as possible.