Breaking out of a Frozen SSH Terminal Session

For a long time I have found that if the internet connection is broken during a ssh terminal session that the terminal hangs and the keyboard is un-responsive - CTRL-C, CTRL-D etc. do not do anything.  I have always just cursed and closed the terminal window.

I just found that ~. will break out of the frozen session, giving you access back to the terminal.   ~? gives a list of other escape commands, but I am not sure what I would use those for.