我们很好奇，怎么可能做到呢？

　　And we thought it must be a hoax.

　　多半是吹牛

　　And we started looking through libraries, looking for the secret tones that would allow you to do this.

　　我们开始泡图书馆，寻找打免费电话的秘密

　　And it turned out that we were at Stanford Linear Accelerate Center one night,

　　一天晚上我们去了斯坦福线性加速中心

　　and way in vaults of their technical library, way down at the last bookshelf in the corner bottom rack.We found an AT&T Technical Journal that laid out the whole thing.

　　在科技图书馆角落的最后一排书架上，我们找到一份AT&T技术手册，揭开了所有的秘密

　　And that's another moment I'll never forget.

　　我永远忘不了那一刻

　　We saw this journal and we thought "My God! It's all real."

　　我们看着这份手册，心想老天这一切都是真的

　　And so we set out to build a device to make these tones.

　　于是我们着手制作能够发出这种音频的装置

　　And the way it work was, you know when you make long distance call you used to hear "dududududu" right in the background.

　　它的原理是这样的，我们打长途电话时会听到嘟嘟的声音

　　They were tones that sound like the touch tone you make on your phone, but with different frequencies so you can make them.

　　听起来像拨电话的按键音，频率不同，但可以模拟

　　It turned out that was the signal from one telephone computer to another,

　　实际上那是从一台计算机传到另一台计算机的信号

　　controlling the computers in the network.

　　它可以控制交换机的工作

　　And AT&T made a fatal flaw when they designed an original telephone network, digital telephone network, was they put the signal in from computer to computer in the same band as your voice,

　　AT&T公司设计的数字电话网络有严重漏洞，他们使用与声音相同的频段来发送控制信号

　　which meant if you could make those same signals, you could put it right into the handset.

　　也就是说只要你模拟出相同的音频信号，通过听筒发送出去

　　And literally, the entire AT&T international phone network would think that you were an AT&T computer.

　　整个AT&T的国际电话网就会把你当成一台AT&T计算机

　　So after three weeks we finally built a box like this, it worked.

　　三周后我们做出了这样的一个装置，真的管用