It should be a big milestone.
How about the following updated Citation?
The first transpacific undersea coaxial telephone cable linking Japan, Hawaii and the US Mainland was completed in 1964. It was a joint project among American Telephone and Telegraph, Hawaiian Telephone Company, and Kokusai Denshin Denwa. Service over this communication bridge was inaugurated on 19 June 1964 by President Lyndon B Johnson and Prime Minister Hayato Ikeda. TPC-1 improved communication between Asia and U.S.A./Europe, and contributed to submarine cable technologies. (69 words)