A secretary in a doctor’s office creates a voicemail greeting that says, “If you have a scheduled meeting with us, we could use copies of all your medical documents from last year, so come prepared.” Using the word “could” gives patients the impression that they don’t necessarily “need” last year’s documents. See the difference between “could” and “need”? Your word choice can impact a future meeting significantly. If you want a customer to perform a specific action, you need to pay close attention to how you express your calls-to-action.
Practice makes perfect. Again, another obvious one, but it has to be stressed. If you want your voicemail greetings to come off as genuine, you have to practice. If you simply throw together a greeting that sounds and feels rushed, your customers aren’t going to let you get away with it. You will come off as if you don’t really care, and that won’t convince anyone you’re prioritizing the customer experience.

On-premise or hosted PBX: This isn't a choice all businesses will face. Small analog phone systems usually come with a simple hardware PBX that's kept on-site. And medium and large businesses often want the control of an on-site PBX, but they also have the IT budgets needed to maintain them.
Creating a voicemail message, particularly for business, is as important to your brand as your business card, email, letters, signage etc. It is imperative the prospective client can confirm they called the right business. Leaving a voicemail is even more important. It is a conversation starter.