HOW TO – Make a cheap “pager scanner”

In this video (m4v) we show you how to take a $10 pager and make “pager scanner” – it can see all the pages and pager data on the pager networks – surprisingly it’s still used for a lot of interesting things and for transmitting data to many devices. Breadboarding diagram for 2-fsk decoding here & download PDW here.

If you want to see how we got here, check out part one first (reverse engineering a pager)… As always, you can get all the videos on Adafruit as we post them through iTunes too… and HD versions on Vimeo.

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  1. What are the legalities involved with this experiment?

  2. Are you a lawyer, why do you care? Cool project Adafruit!

  3. I’d be careful here. Even unintentional eavesdropping on real-time transmissions of content (or even routing information) is illegal. Do you have legal representation for your tinkering? If not, you should (and hopefully no prosecutor decides to make an example… or simply just prosecute). In short: be very very careful when possibly intercepting content or routing information transmitted over communications networks!

  4. Use scanners as an example. Listening to public safety channels or business channels is not illegal. The problems start when you *divulge* what you’ve heard to 3rd parties.

  5. That might be so for unaddressed broadcast networks (where the message isn’t intended for a specific recipient). However, the pager network is more like ethernet where it is a broadcast-but-addressed network… that is, all devices can see the messages but each message is intended for a specific device (or group of devices). And it’s not just a trigger on disclosure… any capture in real-time of content (and/or routing information) is wiretapping (or equivalent to a pen-register).

    Unfortunately, it doesn’t help in the legal analysis to think about what is possible on the device, but instead what the law proscribes. I think you should be careful here and talk to people like the EFF before going further (and if you did, I’d love to see a reflective post on how you decided to go forward with this project).

  6. BTW, I am not a lawyer, but my PhD advisers were. 🙂

  7. And I’ll try and shut up after this one… from Factsheet 2 of the Privacy Rights Clearinghouse:

    “Federal law prohibits anyone from intercepting messages sent to display pagers (numeric and alphanumeric) and to tone-and-voice pagers. Tone-only pagers are exempt from this provision. (Electronic Communications Privacy Act, 18 USC 2510)

    Law enforcement must obtain a court order in order intercept your display or tone-and-voice pager. But under the USA PATRIOT Act, enacted in 2001 following the September 11 terrorist attacks, the standards for obtaining court ordered warrants have been loosened.”

  8. Hmm… That might make a good book — spies using the pager network to send encoded messages back and forth by calling a random pager number and sending a few characters. The person that got the page would think it was a wrong number, prank or a mistake, and the spies wouldn’t have to send to the same pager twice! Only the intrepid hero, with a $10 pager, a computer and a talent for pattern recognition can save the day!

  9. Marc de VInck

    Awesome as usual Limor!

  10. presidentpicker

    stop scaring the kid with this lawyer stuff. decoding pager messages is nothing new. there is no bad intent here. go melt some solder.

  11. I’m not trying to scare anyone; just educate. I’m willing to help if Ada or others want to talk about this.

    @presidenpicker: I didn’t say that this was new nor that anyone had any intent, good or bad. That simply doesn’t matter.

  12. While this is interesting, and has been going on for a while. Be aware as another poster pointed out that, in the US:

    18 USC 2510 covers this and its ILLEGAL, period.

    There have been several cases of groups who were monitoring public safety pages and then send out pages for “incident alert” groups that were very successfully prosecuted. See BNN NY for one:

    Motorola also likes to “flex” its muscle on IP items for software the infringes on its Flex pager protocol. WinFLEX for example was has been hunted by Motorola legal for awhile.

  13. @rec9140 – your link is from 1997… over 10 years ago….

    adafruit isn’t selling anything or passing along news tips to “clients”, they showed how it was possible to do this using software on the web – teaching and instruction for the most part falls under free speech – showing an educational electronics video is a lot different than what these people did…

    “information about emergencies intended only for pagers used by government officials and pass that information on to its clients.. Breaking News Network, a Fort Lee, N.J., news “tip” service, with illegally intercepting pager signals. ”

    besides, it’s likely photoshopped, you can see the shadows, i doubt any of this actually works.

  14. Randomguy is RIGHT when i watched the viodeo carefully you can see that fram 532 anbd frame 634 are very differnt. when i looked at the images the shadow from the breadboard and the monitor doesnt line up at all – totally SHOPPED’

  15. I hate to continue to be a party pooper, but, it doesn’t matter if adafruit sells anything or passes anything on… simply the interception of pager network content for other devices is illegal (and that’s what got the BBN folks in trouble). This has nothing to do with free speech (legally speaking).

    18 USC 2512 is pretty clear: “any person who intentionally … manufactures, assembles, possesses, or sells any electronic, mechanical, or other device, knowing or having reason to know that the design of such device renders it primarily useful for the purpose of the surreptitious interception of wire, oral, or electronic communications … shall be fined under this title or imprisoned not more than five years, or both.”

  16. btw, the people in the BNN case linked to above both ended up pleading guilty to a misdemeanor, paying a $20 fine and being on probation for one year. The company that the worked for (BNN) faced a fine of $500k and ended up being convicted of a felony and sentenced to a $30,400 fine and three years of probabtion. For the legal types out there this is all in S.D.N.Y. and cases are USA v. Gessman (1:97-cr-01198-LB), USA v. Martin (1:97-cr-01200-LB) and USA vs. BNN (1:97-cr-01206-SHS).

    Here’s more NYT coverage:

  17. Joe, don’t feed the trolls … You gave the information, you don’t have to convince everyone that you’re right (but you are :))

  18. presidentpicker

    you are quoting excerpts from 18 USC 2510 that benefit your point. There are many exceptions in that section that you don’t bother mentioning. You are also quoting a case that’s only marginally related. i.e. bnn was profiting from messages and engaging in “ambulance chasing” – totally different intent from limor’s educational video.

  19. presidentpicker++

  20. I’m going to take vic’s advice.

  21. Unfortunately, these people are right. You can show people how to make a cheap pager scanner, but you can’t publish any information you obtained using it. That means you need to remove the screenshots of your monitor showing the information you received or you are breaking the law and can be prosecuted.

  22. (you need to talk to a good lawyer. I know some.)

  23. Will you people give it a rest, already? It’s awesome, it’s cool, it’s hacking. Why can’t we leave it at that?

    If you think you’re doing something illegal, don’t do it. Let others worry about the legality of their own actions. Spending half the day preaching to others about your pseudo-informed interpretation of wiretapping law is, frankly, a waste of time.

  24. Pretty cool project. I’m always amazed when I see someone still carrying a pager but if the tech still works and solves your need, why change it?

    I think I’m going to start a ripping something apart to learn about it day at my house. Probably it will end with “then the magic blue smoke was released…”

  25. If people didn’t break the law on occasion, we wouldn’t be able to expand our knowledge of certain things.

    Additionally, if anyone watches the show the Wire (a police vs drug dealer drama show), the first season had the drug dealers using basic numeric pagers and a simple number code to relay messages.

    It shows the police having to go through the trouble of getting the wiretap warrants for the pagers, and it’s a pain.

    Not saying that TV shows are a source of information, but in this case, my brother works for the DC Police, initially in vice, and then in major investigations, and wiretap warrants for pagers are harder to get then for phones. No one knows how to do it.

    Maybe the police need to look to Adafruit for help sometime…

  26. TheThompsonFive

    If there were cad file attached I would be making this now! All your fear mongering makes me want to do this more, and then present it to a group, and hand out pcb’s.

  27. Fantastic project conclusion! I am looking forward to the next hacked device. 🙂

  28. ladyada,

    Where did you find a pager for cheap ($10)?

  29. i live on canada, i dont think we have a law here for that , hey hey , so i will do it !! Thanks for the good job, reverse engineering is awesome !!

  30. i found mine on ebay but really there are millions of pagers out there so they are out there for cheap -somewhere-

  31. will it work with an pcmcia serial port card thing?

  32. @yon, mm dont know. -probably- but not definitely

  33. TheThompsonFive

    I just bought an identical pager on Ebay. Any chance you could give us a closeup of yours so we can see where you soldered on to it?

    For anyone else that may be interested the seller has seven left and wants $10+$5 shipping:|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50

  34. follow the link to the HD video, you can likely pause it to get a look (let us know if it doesn’t work out…)

  35. TheThompsonFive

    Almost, but the angle is wrong, maybe if I had one of those photo enlargers from Blade Runner. If you would be so kind…

    I have “Hit me on my Beeper” stuck in my head now.

  36. Is is possible to do the same trick with satellite pagers like this one?

  37. TheThompsonFive

    Is the frequency of the pager important? The guy I bought it off is giving me the choice of: 931.6875, 929.2125, 410.4788,


  38. pretty much any frequency that is used in your area will pick something up. but you’ll need to do a little research to figure that out. 929.6625 is used a lot, so i picked up one of those

  39. ladyada,

    Could you post a diagram of where you soldered your leads to on the pager?

    thanks in advance.

  40. wheres the fun in that? 🙂 use a multimeter in continuity mode and the datasheet to figure it out

  41. TheThompsonFive

    Point taken on mikeyd’s behalf. But what is that cap on the breadboard in the video? It’s not in your schematic.

  42. power supply decoupling

  43. Old padgerZ

  44. i just found a motarola flex pager…how much fun can i really have with this..

  45. Damn, that was sexy… the pager mod I mean… umm.. yes.. the mod…

  46. Do SMS messages use the same network? Anyone know of similar for SMS?

  47. Better way to do this is show folks how to design/build a “data slicer” and then tap a baseband audio output from a scanner radio. Then you’ll be picking up any and every pager frequency you want! Been doing this since 1996 when WinFlex and other progs were available you can’t even find them on the internet anymore. P.S. Be real careful, back in 1999 or so there was a guy famous in the scanner scene that got busted for selling info on decoding police MDT and pager decoding. Also the reason the WinFlex folks disappeared…

  48. Just a few notes: I picked up a few of these pagers and wired the pin to bring the power saver high, connected my scope and it appeared to be data on the fsk1 and fsk2 lines however tuning in my unblocked digital scanner to the frequency of the pager proved interesting as I had inadvertantly purchased a scanner with the wrong freq for my area. So just because you see data on the fsk dosn’t mean it’s a message or that there’s anything wrong with your 4level data slicer. I used my scanner to locate about 5 frequencies that cover my area. I connected my scanner to the sound card but I just couldn’t get the volume right. I performed the discriminator install for my scanner (which someone here mentioned) and it works unbeleavably well. My only advice is set your affinity to 0 only and raise the priority of the pdw process to realtime. Remove the squelch and allow the program to determin data from static. Some sound cards I had to have the Microphone unmuted for the pdw needle to shake / see the static. On that computer I just muted the master volume. (tough luck if your trying to listen to pandora and your sund cards like that…

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