The long distance line between the Tohoku region and Hokkaido was opened in 1926 (Taisho 15). Previously, communications between Honshu and Hokkaido consisted of the 15 telegraph circuits installed across the Tsugaru channel. Installation work on the Tsugaru channel submarine cable for long distance telephone lines was completed on April 16 1926 (Taisho 15) and the service commenced on the 24th of that month. The cable spanned approximately 65km between Ishizaki in Aomori Prefecture and Oshima-Tobetsu in Hakodate, Hokkaido.

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