a standard greeting as per Option 5 minus the mailbox user's name, followed by the fixed system prompt, "Begin speaking after the tone, then hang-up when you are finished or press any key for further options."
If your job involves a lot of talking on the phone, take the time to learn the NATO phonetic alphabet. "If you need to spell something out, you'll always have a way to clarify which letter you've said without having to think about it, and it sounds more professional than, 'B as in boy, L as in...uhhh...Larry.'"

Voicemails can give an important message or inform the caller about the receiver’s status. Thus, it is important for you to be clear while recording such messages. Here are a few examples of voicemail greetings to get an idea about appropriate messages that can be recorded the next time you leave your house or desk.
Hello! Thanks for calling [LinkedPhone’s Customer Success Team]. We are currently helping other customers achieve their goals and want to do the same for you! Please leave a message with your name, number, and a brief description of how we can serve you. We promise to return your call [before close of business today]. In the interim, you can also check out our website at [linkedphone.com] for helpful answers to our most common requests. Thank you.