I have a need to allow only 1 person access to a specific 1900 number. My current configuration has 1900 set as an FRL of 6. In order for a user to dial 1900, I would just change the NCOS of there set to 6 and change it back when they are done. Now I have a user that will need to call a specific 1900 number ongoing. How can I allow 1 user to dial a specific 1900 number at any given time, yet still block the rest of the users from dialing 1900 all of the time?