Leave out excuses like “I’m probably with a client right now” or “I’m unable to answer the phone right now” – it’s obvious you can’t answer your phone if a caller is listening to your voicemail greeting!
a standard greeting (as recorded by the administrator or other person), followed by the mailbox owner's name (as recorded by the owner), and then the fixed system prompt, "Begin speaking after the tone, then hang-up when you are finished or press any key for further options."

When you create a professional voicemail greeting, it can be a good idea to think about what your callers might want to know. After doing so, you can make a list of points to cover in your voice message; it might also be a good idea to write out the entire greeting on a piece of paper. The ideal message should be somewhere between 10 and 20 seconds, so you may want to time yourself repeating your message before you record it. After composing your telephone message, it can be a good idea to get a second opinion of this greeting so you can make sure it sounds professional. Writing down a voicemail greeting helps prevent mistakes when recording it.
It can be quick and easy. “Thank you for calling Davissa Phone Systems.” If you identify your voicemail right away, people will feel more confident in leaving their message, knowing it’s going to the right place.