if there is a noise per se, I would say. I can barely hear you, there is too much static. If you have a bad connection and no noise problem as with your video calls, you could say We have a poor connection, you're coming in and out. Or you're cutting out a lot...or your frozen...can you hear me??? :o)

You can tell the other person " I can't hear you, the connection is poor" or (if they are a native speaker) "I'm sorry, you're breaking up".

Discrete = Incorrect Choppy = Correct Other ways to say are " There's a lot of noise in the connection". I frequently use "Your voice / The Audio is breaking" but I am not sure if that comes under formal English :)