This also takes me back to watching some modems have bad implementations of the USR protocols. Some were so bad that they'd actually watch the packet traffic fo

This also takes me back to watching some modems have bad implementations of the USR protocols. Some were so bad that they'd actually watch the packet traffic for commands. I remember seeing people getting knocked offline from someone typing ATH0++ over IRC (all plaintext!), and their modem catching it as an actual USR command (the Attention-Hang Up command).