I'm not sure I follow you.
Are you saying that from phone A, you can contorl the Class of Restriction on phone B?
If so, then you could look at using a product like UCCX to take input from phone A, and set CoR for phone B, then utilize PLAR for phone B, such that all calls route through UCCX, checking for CoR before completing the call.
Setting:
Phone A > UCCX > PIN > Phone To Set > Toggle CoR > End
Restricting
Phone B > PLAR > UCCX > Get Digits > Check CoR > Accept or Reject > End