https://smith.ai/blog/28-business-voicemail-greetings-for-main-office-and-personal-numbers-formal-informal-modern-and-just-hilarious
As greeting messages should reflect your mood and your personality, they must be recorded with utmost care and with the right choice of words. Here are a few examples which you can make use of while recording your own greeting messages.

Do they want to sit through an IVR menu that may or may not direct them to the right person? Do they know you’re a one-man/woman team and there’s no reason to sit through a menu? Skip the menu entirely and let them leave a message as quickly as possible. There’s no reason to add any additional steps or make your customers go through leaps and hurdles to leave a simple voicemail. When you identify what your customers’ pain points are, you make it much easier to determine what you want them to do to save everyone from the unnecessary stress.
Business professionals are also encouraged to keep their voicemail organized. Delete any messages from the office phone that are no longer necessary after calls are returned, and write down any phone numbers that are needed at the time the message is listened to. If modern voicemail service is utilized, such as that supplied by Voicemail Office, in which voicemail and fax messages are received in a staff member’s email inbox, the individual should write a short explanation in the body of the email if forwarding any voicemail messages to other staff members.