From the My Phone Service page, scroll to My voicemail and select Set up voicemail. Choose your voicemail box type. Select Advanced voicemail (suggested method), and then select Next. Subaccounts voicemail access and phone number assignment. Add name and assign each phone number a name to easily identify who is using the line. Select Continue.
When you're in a call, wait for the Add Call button to light up, so you can add a third caller via 3-way calling. Tell the other person to wait, click the button, and call yourself. Stay on the line and listen to your own voice mail greeting, then for the tone that indicates recording has begun. Tap Merge Calls. All three calls are merged—and the third one (your voice mail) is taping the other two.

With notifications, you're alerted when you miss a call or receive a voice mail message. You can decide how and when you want to be alerted. For example, you can receive an email when you miss a call or get a text message when someone leaves a voice mail. By default, you'll receive an email anytime you miss a call, but text messaging notifications are turned off.
You might also consider giving them the option to skip your voicemail message completely by pressing another key (again, check with IT). You also want to make callers aware what you will return their call, instead of telling them that you will try to return their call--and let them know when you are likely to do it, if possible. If necessary, provide additional or emergency information in your voicemail greetings. My dentist, for example, lists his cell phone number for emergencies.