Well, as good a time as any to remember an old exploit.

Back in the old days, to put the modem back in command mode, you had to send it +++ and wait one second without sending anything.

Hayes, a modem manufacturer, owned a patent on this "and wait one second" idea. Some manufacturers had to implement this idea without that one second.

Then came the Internet, and with it the ICMP protocol, which is a neat way to make a remote connection repeat stuff back to you. And lo and behold, you could send a ICMP packet with data that contained "+++ATH0" and when echoing back the packet your modem would pick it up as a command and disconnect. Same goes for IRC /ctcp ping commands, and many other protocols.