UNDERGROUND

up bits of the telephone exchange along with any line techni- cians who happened to be working on the cable at the time. Telecom had protective fuses which stopped electrical surges on the line, but BBS hackers had reportedly developed circuit plans which would allow high-frequency voltages to bypass them. Other members of the underground considered what sweet justice it would be to set fire to all the cables outside a particular Telecom exchange which had an easily accessible cable entrance duct.

It was against this backdrop that the underground began to shift into phreaking. Phreaking is loosely defined as hacking the telephone system. It is a very loose definition. Some people believe phreaking includes stealing a credit card number and using it to make a long-distance call for free. Purists shun this definition. To them, using a stolen credit card is not phreaking, it is carding. They argue that phreaking demands a reasonable level of technical skill and involves manipulation of a telephone exchange. This manipulation may manifest itself as using computers or electrical circuits to generate special tones or modify the voltage of a phone line. The manipulation changes how the telephone exchange views a particular telephone line. The result: a free and hopefully untraceable call. The purist hacker sees phreaking more as a way of eluding telephone traces than of calling his or her friends around the world for free.

The first transition into phreaking and eventually carding happened over a period of about six months in 1988. Early hackers on PI and Zen relied primarily on dial-outs, like those at Melbourne University or Telecom's Clayton office, to bounce around international computer sites. They also used X.25 dial- outs in other countries - the US, Sweden and Germany - to make another leap in their international journeys.

Gradually, the people running these dial-out lines wised up. Dial-outs started drying up. Passwords were changed. Facili- ties were cancelled. But the hackers didn't want to give up access to overseas systems. They'd had their first taste of inter-