Your scenario should already be set up. More than likely a call comes in on an extension group. Probably 5001 or something along those lines. Go into the voice mail and check the forward station group. It probably has something like 5001 goto menu xxx or mailbox 5001. In that menu or box is the information missing here. We need that in order to better direct how to make this work.

If it is going directly to a mailbox then check the box and the extension in the voice mail. The options will be pretty clear. If this is the case you can change the number by logging into the box.