One way is to have a Translation pattern so that Directory numbers for calls can be masked.
In CCM Admin
Go to Route Pattern->Translation Pattern
Configure a
1.Translation pattern number say 2211.
2.Under Calling party Transformation
1st option : Configure the Calling party transformation mask =2111
Destination phones will display '2111'
2nd option : Calling Line ID presentation = Restricted.
Destination phones will display 'Unknown Number'.
3.Under Called party Transformation
Called party Transformation Mask= Pilot Point Number (=2111 , in our case)
Originating Phones should dial 2211 as pilot point number( Internally this is being converted to 2111 by Translation Patterns)