Many moons ago when I played baseball in college catchers called their own game (does that happen anywhere nowadays outside of professional baseball?) so the only signs we would try and get would be bunt,steal, hit and run etc. We never had guys on second try and decipher catchers pitch calling but it is certainly
done.
Our catcher calls all our games, HS varsity level. We talk between innings about what she's seeing with hitters and which pitches are most effective. She's young, learning and is really starting to call a good game.
The story above was from quite a few years ago, when wristbands were just starting to be "the thing". We use them now for offense, but not defense.