Log in to www.myvoiceportal.com
Note: You must be an "Office Manager" in order to make these changes.
At the top of the page you will need to click on "Manage Organization"
Next you will need to click on "Auto Attendants"
Next select the Auto Attendant you wish to change the greeting for by clicking on then name of it.
Next hover over the speaker button and it will display Manage Audio then click that button.
Next enter a description and select "Record" by clicking the circle to the left of Record then it should populate your extension in the call me at window.
Now click on call and this will ring your extension. Follow the instructions and you should be finished.
Note: This can all be done remotely if you need to do this when out of the office. All you will need to do is put a phone number (Like a cell phone) in the call me at window. The number will need to be 10 digits as follows: 3175555555