If you give the user a unique COS, where the "Client Room" has been turned on, when the station makes an outbound internal call, the extension is not displayed but the information in the "Room" field is.
I don't know of a way to surpress the display of the name, but you could give him/her a bridged appearence of a station where the name has been left blank or set with a generic name.
Susan
"Opportunity is missed by most people because it is dressed in overalls, and looks like work." - Thomas A. Edison