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Phreaking out: a history of phone hacking

Computers haven't always been the sole domain of hackers

A picture of a retro phone handset against a blue background

When people talk about hacking, it’s more often than not associated with the internet. Throughout the later half of the 20th century however, long before the internet rose to worldwide dominance, the hackers of the time caused mischief in other ways. “Phreaks”, as they were called (a combination of “phone” and “freak”), used to manipulate telephone networks into performing actions that were not intended.

Most phreaking took place in the United States and one of the more famous techniques used was known as red boxing, a practice that involved tricking payphones into thinking that a coin had been inserted without actually inserting anything. Phreakers would play a “red box tone” into the phone — a sound that imitated the actual sound generated when a coin was inserted — to trick the phone into thinking it had received a quarter. Phreakers would play a multi-frequency tone operating at 1700 Hz and 2200 Hz simultaneously 5 times for 33ms each with 33ms pause in between each tone using a modified tone dialler, otherwise known as a red box — a term rumoured to have been conceived after the first person to use the technique coloured their tone dialler red.

In the era before cheap phone plans, long distance and overseas calls could cost up to $15USD to even dial. Phreaks took advantage of their free calls, calling people from all over the world whenever they liked. Some phreaks also turned a profit through red boxing. Using a red box, they would intentionally call a disconnected number, before calling the operator to ask for a refund. Usually the phone company would offer to mail a cheque for the coins that were (apparently) deposited.

A much riskier variant of red boxing also existed. It was called “beige boxing”, which, in essence, consisted of wiretapping a landline telephone. Phreakers would find the telephone network interface — typically a beige box — on the side of a house, insert a couple of their own wires, and all of a sudden have the ability to answer and call on others’ behalf. Because telephones operate on analogue signals, it’s both extremely simple and dangerous to make your own beige box with a landline phone. As beige boxing involves meddling with wiring, any phreaker doing so when the phone rings could be in store for a nasty shock.

Phreakers took privacy invasion to new levels when it came to answering machines though. One feature that many answering machines had was remote administration, meaning you could call from another number and check if anyone had left you any messages. If you wanted to do this you’d have to enter a password, though most users didn’t bother. A lot of answering machine brands had default passwords, meaning all phreakers needed was a copy of the user’s manual to access people’s messages remotely. Answering machine passwords were often very short and could only consist of numbers. Using a variety of tricks, phreakers could usually guess a password after a few minutes of inputting numbers. Through use of the De Bruijn sequence — a method that allows for every possible combination of numbers to be inputted — a three digit password could be cracked in just over 1000 key presses.

Phreaking as it was in the past is dead. A lot of the time when people talk about “phone hacking” nowadays, they tend to be referring to jailbreaking or rooting a mobile phone’s operating system. Hardly anyone uses payphones anymore, and many systems have received upgrades that made previous attacks obsolete or much harder to perform. It is unlikely that you will find a payphone in the States that you can redbox. In recent years many people are opting to not have a landline phone, making beige boxing a thing of the past too. As we transition into the future, it’s likely that opportunistic hacking like redboxing will become a thing of hacker nostalgia.