Is the phone trick from the movie Wargames possible?

I just saw the movie Wargames, and am now wondering about something I saw in it. There’s a scene where Matthew Broderick’s character wants to use a payphone, but doesn’t have any money. He bypasses having to pay by unscrewing the part you talk into, and then touching the inside to part of the payphone unit. Was this possible at the time the movie was made?
I know this is poorly described, you’ll have to have seen the movie probably.

While I’m at it there was one other part I was wondering about. There’s a scene where he’s locked in a room with an electronic keypad lock. He gets around that by getting a tape recorder, having the guard open the door to talk to him, and then taping the combination tones. After the guard leaves and closes the door, he plays back the tape and the door unlocks.

AFAIK, it once worked but it probably wouldn’t have worked when the movie was made (pay phones haven’t had mouthpieces that unscrewed since the 60’s, for one). Most payphone hacks that you read about or see in movies are very old-fashioned and haven’t worked in years. You used to be able to use a whistle that came with Cap’n Crunch to make free long distance calls (the whistle coincidentally put out the exact tone necessary). You could also tape record the sounds of money dropping and play them over the phone to get extra time on your calls, etc.

That’s more like it. Yeah, that might work. Problems: I have a hard time believing that it would be possible to easily access the lock from inside the room and really, really have a hard time believing that it would be readily apparent even to someone who understood technical things as to which wires are the ones to connect the tape recorder to. This is a common conceit in movies, e.g., car thieves always reach under the dashboard where two wires are conveniently waiting to be joined together to start the car.

I haven’t seen the movie since it was in theaters, so my memory’s fuzzy, but the computerized lock, depending upon the model, could actually be insanely easy to hack. 2600 magazine printed the possible combinations for those type of locks about a decade or go, and the longest time it would take you to run through the combinations was about 30 minutes.

Funny that you should mention 2600 magazine, for it’s named after the exact tone that was used to make those free phone calls.

At the time of the movie that trick did work(or atleast had worked recently in the past). The problem was as Malienation said the phone companies started gluing the mouthpiece shut. The tape recorder trick might have worked. He wired it up the mic to the keypad so he didn’t record the sound the buttons made, but recorded the electrical signals they sent. Then he played them back into the lock. This is possible, but the electrical signals would have had to be in the range that the tape recorder could have recorded.

The Cap’n Crunch whistle and most of the phone hacks of the time worked off the same princaple. The pay phones were actually pretty dumb. They didn’t know how much to charge for a phone call. The main system back at the phone company did. A pay phone was connected to a special phone line that the computer would listen to. What the phone did was send a tone back to the computer for every 5 cents you deposited. So if you dropped in a quarter it would send 5 tones. This tone was sent over the same line you spoke on. People got smart, and recorded these tones. Then they would just play them into the handset, and the computer would think you put money in the phone.

Then the phone company got smarter, and disabled the mouthpiece on the phone till someone answered the other end. Of course this didn’t stop people from using it to continue calls.

These days the payphones are smarter. They no longer are connected to a special phone line that is monitored by the phone companies computer. They connect to a regular phone line and each one has a chip in it that is programed with the cost of phone calls to all country codes, and area codes. No more sending tones down the line to calculate costs. It is all done in the phone. Yes there are ways to beat the system, but that is left as an exersize for the reader.


Corbin made a mechanical “Sesame” padlock with only 4 wheels but 9,999 combinations +“0000”.
Each combination required depressing the shackle as far as it would go and releasing to open or reset the wheels to the next number.
It took hours to find a ‘lost’ combination for customers. A new lock was cheaper by far.
Sometimes luck would turn up the combination quickly and other times it might take several thousand attempts.
The lock, when open, could be reset to a new combination.

Over the years the manufacturers (Corbin and now Master Lock) have tightened up tolerances and used better materials to where just about the ONLY way to open one is to run thru the combinations.

I saw Wargames, but I don’t recall the scene you’re talking about. In any case, I personally did something very similar to this in high school (late 1980s).

The trick was done like this. You straightened one end of a paper clip and poked the pointy end into the mouthpiece of the phone, such that it made contact with the metal inside. You then took the rounded end of the paper clip and made contact with the keyhole for the change thing. It was then possible to make one phone call anywhere in the U.S.

I don’t remember how I learned this. I certainly didn’t figure it out myself.

IIRC, folks from the phone company showed up to spray some sort of coating on the keyhole that would prevent people from doing this, but it would be quickly removed with a piece of sandpaper or such.

I did this more than once, it was actually to headset - not the receiver end you would use in the 1980s - up to some time in the early 1990’s it still worked for me.

I don’t know if this is illegal to post, because I am sure it doesn’t work anymore, so it is useless knowlege unless you get a time machine. And also this is from memory, so I might have missed something.

Because the receiver end came out like a watch battery, that end was useless, but you could open the head set, take out the speaker, and there were two screws attached to the back of the speaker that had wires connected. You would then touch the screws (I can’t remember if it was one or both) to the metal on the sides of the cradle with the connection closed, you would then lift the cradle to open the connection, and if you heard a click - you had created the circuit which would allow you a free phone call. But you could also get a nasty shock too!

After this click/shock, you could then dial.

Just an aside about the movie. The room he was imprisoned was not a jail cell, but rather just a room with a lock. Desigining such a room would usually consider the outside of the room as the side facing the “intruder”, and the locking mechanism would be on the inside, or “safe” side.


Silly question - if he was able to access the electronic lock’s “mechanism” why didn’t he just jumper the latch and skip the whole man-in-the-middle replay attack?

What was the combo on that lock anyway? The tones sound similar to 444666, if my fuzzy memory is any good.


Oh dear. Sorry about that – I was attempting to remove a keycap from my keyboard, and apparently firefox had focus. I’m not sure what sequence of keys moves one to the reply box, or posts what’s been typed there, but apparently, I pressed them while wrangling with my ‘D’ key and two paperclips.

At least my ‘D’ key is working again. If someone wants to report that to a mod, I’ve no objection to seeing it (and this) removed.

Huh. And here, I thought that was meant to be a phonetic reproduction of one of the phreaking sounds.

Thanks for the answers. This is fascinating stuff. It’s before my time as I wasn’t born until 1986, but it interests me anyway. Now I feel like watching MacGyver or something.