The distress signal used on the Titanic was the "CQD" code, which stood for "Come Quick, Distress". It was the standard maritime distress call at the time.
While the Titanic did use the newer "SOS" code, it was not a new distress code. It was introduced in 1908 and was becoming more commonly used by 1912, but it was not the primary or exclusive distress call.
The Titanic sent both "CQD" and "SOS" signals in their distress call. It's important to note that the "SOS" code was not a replacement for "CQD" and was more of a supplementary signal. The reason the "SOS" code became famous is that it was more simple and easier to understand, even for untrained operators.