The bad news is that, if you are a millennial, you cannot afford to regard leaving voicemail messages as obsolete. There are four generations actively participating in the workplace. This is unprecedented. It means that, while Baby Boomers are learning to text, millennials also must become adept at using voicemail.
I’d bet good money that most voicemails never get played. Instead, they just sit there serving as extra “missed call” notifications, letting you know to call or text back whoever bothered to leave you the message in the first place.

A relatively unprofessional one — like mine, for instance — does the opposite: It encourages prospects, recruiters, and potential connections to run in the other direction.
If you can, try to keep your message 20 to 30 seconds long — max. This is the sweet spot for sharing just enough information without going overboard, potentially getting cut off by the recipient’s voice mailbox system, or having the listener hang up early because your message was simply too long. Speak clearly, avoid rambling, and get straight to the point.