Assign this phone to a particular COR, let's say COR 10. Perform a 'change COR 10' and set called party restriction to whatever your preference from below may be.
Called Party Restriction - Enter one of the following: "inward," "manual," "public," "termination," or "none."
Inward - Blocks the calling party from receiving incoming
exchange network calls, attendant originated calls, and attendantcompleted calls.
Manual - Blocks the called party from receiving all calls except for those originated or extended by the attendant.
Public - Blocks the called party from receiving public network calls. Attendant calls are allowed to go through to the called party as are attendant-assisted calls if the Restriction Override field in the public restricted station's COR is set to "attd" or "all."
Termination - Blocks the called party from receiving any calls at any time.
none - No called party restrictions.