The single number service was formally introduced in December 1945 (Showa 20) as an initial step towards reconstruction after the war. This service enabled customers with more than one telephone line to receive calls on a single number on up to the number of lines registered as single-number lines. At present, the single number service is available as the minor single number service, the major single number service, the special major single number service, the multiple number selection service and the special distributed single number selection service. There are no usage and installation fees for these services.

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