[hiroprot]

That brings back fond memories. In high school (a long time ago), I coded up a client-server application in Perl/Delphi to utilize the ISDN D-channel to transmit small amounts of data by repeatedly dialing a destination, using the call initiation metadata to communicate, and then hanging up before the call got established.

In Europe at that time, every call (even local ones) started getting billed as soon as the dialed party picked up. So effectively, this allowed for fee-less small applications that didn't need much data, but that I wanted to invoke many times a day (think checking email, checking server status, IM, etc).

[missingjdubb]

This is the coolest, old school hacker tech I've heard in a while