A formal voicemail greeting is one with a professional tone. It could be for a business or for personal reasons. Formal voicemail greetings are designed to impart a sense of authenticity. They leave the caller with a sense of trust in your abilities, whatever they may be.
Rehearse or write down your message before recording it. Remember that old saying “practice makes perfect?” It’s certainly true when it comes to creating an electronic greeting. The more you’ve rehearsed, the easier the message will be to restate. If you don’t have time to practice, writing down the greeting before recording it – and then reading it aloud from the paper – may help you stay focused on the correct wording.

Expanding on the simple approach above, let the caller know who they've reached. This will not only eliminate people leaving voicemails by mistake, but it will reassure the caller that they have called the number they intended.
Sometimes, it’s best to pick up the phone instead or have a face-to-face meeting if the tone or topic of the email is emotional, terse, or needs a lengthy discussion. Responding to workplace texts: You don’t have to have the last word. But if you need to say thanks or okay, say ‘thank you’ or ‘okay’ rather than ‘thankU’ or ‘k.’