Abstract: A calling telephone number information substitution mechanism employs an automated calling number substitution template to selectively modify ‘calling’ party number information that is transmitted to the called party. This serves to associate the calling party who has placed a call that cannot be directly dialed from an outside phone with a valid telephone number identified with the premises originating the call. As a result, the called party, such as a 911 emergency facility, is able to correctly locate and place a return call to a valid telephone number at the premises from which the call has been placed.