In order to promote direct-dial long distance calling, public phones which accept 100-yen coins are introduced on a test basis in parts of Tokyo, Osaka and Nagoya in September 1971. Favorable comments such as "it takes less trouble to feed in coins," and "you don't have to listen the (payment) chimes" lead to full-scale adoption by December 1972. The new phone has slots for both 10-yen and 100-yen coins, and initially looks the same as the large size "blue phone." With full-scale service, the color is changed to the now-familiar yellow.

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