On This Day in Telephone History September 15TH 1969 Boston-Miami Underground Cable Went Into Service. The final link in the Bell System's 1800 mile Boston-Miami underground "hardened“ cable went into service between Cheshire, CT and Blackstone, MA. The hardened cable was an analog L4 carrier cable (coax) carrying general toll circuits as well as critical military communication circuits such as an AUTOVON 4-wire switch as part of the switching fabric of the critical global military communications network.

On This Day in Telephone History September 15TH 1969

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On This Day in Telephone History September 15TH 1969 Boston-Miami Underground Cable Went Into Service. The final link in the Bell System’s 1800 mile Boston-Miami underground “hardened“ cable went into service between Cheshire, CT and Blackstone, MA. The hardened cable was an analog L4 carrier cable (coax) carrying general toll circuits as well as critical military communication circuits such as an AUTOVON 4-wire switch as part of the switching fabric of the critical global military communications network.