Finally, make sure to speak clearly and slowly. Don’t mumble, and make sure your greeting is free from background noise. Nothing paints an unpleasant and unprofessional company image more than a voicemail greeting with static noise, traffic sounds, or colleagues talking in the background.
Note: If necessary, delete an existing greeting (limit of 2 greetings) to make room for the new greeting: Tap the Menu key, tap Delete greetings, tap the check box next to the desired greeting, and then tap Delete. Tap the Record icon to record your greeting. Tap the Stop recording icon to stop recording.

Listen to your messages and return your calls as soon as possible. Of all the lines of communication available (social media, text, email, etc.,) your callers resulted in picking up the phone to call you because they wanted to speak with a live person. Do them the common courtesy and give them a call back when you first have the chance.
The alternative is simple: Provide in your voice message a phone number and refer the caller to an assistant, a colleague, a cell number—any way of expediting their quest. Help your caller to reach someone who can, in your absence, be helpful and succeed in keeping the business. And remember to update your voicemail message when appropriate.