What code was used in the navy before introducing SOS?

Land Telegraphs traditionally used 'CQ' and the Marconi company added a 'D', ''distress'' to 'CQ' in order to create its distress call. ''CQD'' was one of the first distress signals adopted for radio use. Germany's Notzeichen distress signal of three-dots/ three-dashes / three-dots was adopted as the international Morse code distress signal. This distress signal soon became known as ''SOS''. By the February, 1904, the Marconi wireless company required all of its operators to use ''CQD'' for a ship in distress. RMS Republic was collided with the Italian liner SS Florida, Masachussetts, US., while Jack Binns sent the ''CQD''. In April,1912, RMS Titanic radio operator, Jack Phillips initially sent ''CQD''.

Harold Bride, the junior radio operator, suggested using ''SOS''. Philips thereafter began to alternate between ''CQD'' and ''SOS''.