Up to this time, local calls were charged at 7 yen per call, regardless of the call duration, whereas long distance calls were charged based on the distance and duration of the call. This resulted in a significant pricing disparity between local and long distance calls. To eliminate this disparity, proposals for the rationalization of telephone charges were investigated and implemented on November 12, 1972 (Showa 47). The wide area time-based system enlarged the minimum charging area from the subscriber's area to the unit charging area and changed from the "charge-by-call" system (in which there was no limit on call duration within the subscriber's area) to the "time-based" system. This eliminated the pricing disparity between local and long distance calls.