Didn't the radio operator on the Titanic send "CQD" and not "SOS"? CQD being the distress call (hence the "D") at the time--before SOS was developed and replaced it.
As AE4RV points out, both CQD and SOS were used in the Titanic disaster. It wasn't the first time SOS was used, either; it had been adopted years earlier. It was "new" to the operators on Titanic because the Marconi Company they worked for had only recently adopted it.
Jack Phillips and Harold Bride were the two radio operators on Titanic. Technically they were not part of the ship's crew; the Marconi Company supplied the equipment and operators under contract to White Star.
Most ships of those days only carried one radio operator, but Titanic and her sisters carried two because of the high volume of passenger traffic.
Radio was so new and unregulated in 1912 that different companies had different procedures, equipment and methods. The Titanic disaster pointed out the need for more regulation and uniformity.
73 de Jim, N2EY