Telco 214.

Telco 214 is the name block explorers give to a miner that found 1,830 Bitcoin blocks between 19 December 2014 and 23 August 2017. In 2015, its busiest year, it found about one block in fifty. Its blocks carried no name, so explorers recognise them by the addresses their rewards were paid to, which the developer James Hilliard first listed under that name in May 2015.

Nobody has said publicly who ran it. Explorers link it to telco214.com, a company website that never mentioned Bitcoin.

Each block paid its reward to one address, or from late 2016 almost all of it to one address and a little to a second. That reward is separate from the transactions confirmed inside the block. Its last nine blocks, in August 2017, carried the tag “NYA”, for the New York Agreement, a plan backed by most miners that summer to change Bitcoin’s rules. It found no blocks after 23 August 2017, and no announcement about why has been found.