If you only check and return messages once a day or once a week, let your caller know. This will avoid multiple messages by the same caller.
Your phone system can be a powerful marketing tool for your business, and that includes your voicemail greeting. If you want to utilize this opportunity to throw in a quick humblebrag and keep callers informed of your awards and accolades, there are a few best practices, you should follow. First, keep the self-promotion brief and appropriately placed within your voicemail message. Don’t promote yourself and your products/services in the same greeting, and finally, only include current achievements in your business voicemail greeting.

1. Access your digital voice mailbox through your smartphone's touch screen. On an iOS phone, tap on the Phone application and then look for a square in the bottom right hand corner of the screen that reads Voicemail. Tap this button and your voice messages will appear on the screen. Click on any of the messages and press Play to hear the message. On an Android phone, a voicemail icon will appear at the top left of your screen in the Status area if you have an unread voicemail. Swipe your finger down from the top of the screen to view your notifications and then press New Voicemail. Your phone will dial the voice mailbox.
In certain situations, it’s a good idea to let a call go to voicemail. If you’re in a loud area, unable to spend 10-15 minutes talking, or are otherwise distracted, don’t answer. Recruiters who cold-call candidates will understand that you’re simply unavailable – but make sure to return calls in a timely manner. If possible, call back during regular business hours.