When you have new voicemail, the Phone tab in the Skype for Business main window displays the number of your messages. See Contact Card opens the caller's contact card, which lists their phone number, email address, office location, and so on. Open Item in Outlook provides more information about the call.
2) Always mention the name of your business in the voicemail, and if the greeting is for a desk extension, be sure to state who the caller has reached.

If you don’t know it by now, you might never know. Voicemail greetings are incredibly important to users. It conveys identity, character, and image to callers. In an increasingly digital world, where business is conducted online and over the phone, phone presence is increasingly important. As such, your greeting is a crucial part of the platform. While there are a number of obstacles to be aware of, utilized properly, voicemail greetings can be incredibly helpful and beneficial; therefore, its in users best interest to invest themselves in creating a quality recording.
Provide as much useful information in your business voicemail greeting. However, be sure to keep it short and concise. An excessively lengthy voicemail can be damaging rather than helpful. Keep your voicemail to around 20-25 seconds maximum.