If I grant users the permission to change their outgoing Caller ID, they can select between many options, like the main company number, etc... I only want them to be able to select from a restricted set of numbers, not all of them.
I'm not sure you can restrict the access, once they're able to change I think they're allowed to change to any number. but this does raise a new option to have while establishing settings. to be able to create a pool of numbers that are able to be used by certain extensions sort of like a park group. "allow access by extension"