Does anybody know if this actually happened?

The Californian did send out warnings I believe, but Jack Phillips died trying to find help. I believe he took his job very seriously, so I don't think so. The Californian failed to help the Титаник anyways...

Jack Phillips didn't do that but it is true that number one there were ships closer than 4 hours. The other ships thought the flares were fireworks and that Титаник was celebrating. And two the door at the end of the movie that has Rose on it was actually big enough for two. They actually took a computer and generated this. So Jack would have lived if he'd actually gotten on the door.

This actually did happened. I have the collectors edition of movie with all the deleted scenes, and there is a scene where he does send a rude telegram to an officer on the Califorion. And this did happen in real life. The officer on the Calidorion was trying to warn Титаник about ice, but the officers on Титаник had a lot of passenger letters to send so Jack Phillips to him to "Shut up, I'm working bloddy cape race!" if I am correct:)

I would have to say no because if it did happen Ты would think it would have сказал(-а) something in the movie или at least in a book.

Yes, that actually did happen. The Californian was surrounded by ice and was stopped for the night a few miles away from where the Титаник was. The Californian's wireless operator was sending out a warning to Titanic, but Jack Phillips was overworked from sending out so many passenger letters that he snapped at them for the inturruption. And of course the Californian turned off their wireless for the night shortly after and never got Titanic's distress calls.