A method and system for automatically completing long distance, international and local telephone calls using a preselected discount telephone service. A R.A.T. sensor array monitors a telephone line for activity. When the dialing of an outgoing call is detected, a central processing unit, in conjunction with a DTMF decoder, determines whether the call being made is a discount call by detecting whether predetermined positioned digit(s) is a predetermined number or set of numbers. If the number dialed is a discount call, the DTMF generator dials a predetermined prefix and/or access code resulting in completion of the call at a discounted rate.