Can multiple users change settings on the box at the same time using the Internet configuration tool? Sometimes we can't save a change because we don't have the relevant permissions. What is required for read or read / write permissions?

Multiple users can view VOIP settings simultaneously via the Web or GUI, but they will not all be able to make changes. Only the first person to access the voip will have read / write access. Subsequent users will be granted read only permission, which allows them to view, but not change, the configuration. When the first person to access the voip exits configuration, the next person in line will be given read / write permission, etc. Exiting the web interface without, first, selecting Logout from the menu pane may also cause you to receive read only permissions the next time you enter configuration (even if you are the first, or only, person to do so). Power-cycling the voip will grant you full access again.

You should allways password protect the voip with the GUI via serial port if it is on the public internet.