Yes, the bar should be going up SLOWLY. One will scream "You got data for me?" The other will scream 'Yeah bud here you go: AAAAAUUUUUAAAAAAUUUUUUU' "Okay i got that, next" 'AAAAUUUUUUUWOWIEGRRRRRAAAAAAAAAAH' "There was an error in that scream bud can you resend that?"
I believe Petit Professor has a tutorial on how to use it.
Personally, I leave the room when they are screaming at eachother otherwise small noises you make will disrupt the data transfer.
I think petit modem is super cool. Super retro, we just need casettes :p