Tearing Down the Boss Phone

Poke around enough on AliExpress, Alibaba, and especially Taobao—the Chinese facing site that’s increasingly being used by Westerners to find hard to source parts—and you’ll come across some interesting things. The Long-CZ J8 is one of those, it’s 2.67 inch long and weighs just 0.63 ounces, and it’s built in the form factor of a Bluetooth headset.

A couple of months ago Cory Doctorow highlighted this tiny phone, he’d picked up on it because of the marketing. The lozenge-shaped phone was being explicitly marketed that it could “beat the boss”. The boss in question here being the B.O.S.S chair—a scanning technology that has been widely deployed across prisons in the U.K. in an attempt to put a halt to smuggling of mobile phones to inmates.

The Long-CZ J8 is just 2.67 inch (6.8cm) long.

I wasn’t particularly interested in whether it could make it through a body scanner, or the built-in voice changer which was another clue as to the target market for the phone. However just the size of the thing was intriguing enough that I thought I’d pick one up and take a look inside. So I ordered one from Amazon.

It’s hard to get across how small this phone is, at 68mm×23mm×11mm it’s about the size of my thumb, and it weighs just 18g.

It is pretty easy to lever the casing of the phone apart with a metal spudger, because there are no screws. Although if you want to have a go yourself, you should be careful to start on the side away from the SIM card slot as it turns out the two halves of the phone are connected by some flying wires.

Opening the phone up reveals a 260 mAh battery—which provides up to 5 hours of talk time, or 3 days on standby—charging is via the micro-USB port at the top of the phone. The battery is connected to the main board with two wires. On the same side of the phone is a speaker, used when the phone is hooked around the ear like a Bluetooth headset.

The Bluetooth antenna is nothing more than a small length of wire that can be seen to the right of the RF shield, just down from the speaker.

Teasing these out of the back shell is again a job for a metal spudger and doesn’t present a problem. Popping the main board out of the other half of the case also involves prying the microphone out of the case before you can put any force on the board.

The disassembled Long-CZ J8.

The front shell contains the rubberized keycaps as a separate insert, and another small speaker located above the screen that can be pried out with a craft knife—it’s glued into the shell, but the glue isn’t particularly sturdy.

The main board is mostly covered by an RF shield, with the micro-SIM card slot just below it. Flipping it over we can see the small TFT screen, the keyboard, and some LEDs that light the keycaps up when the phone is in use. If you want to you can pry the white keyboard overlay up with a fingernail to reveal the circuit board underneath.

The screen itself is glued (tacked might be more accurate) down to the main board and can be gently pried up with a fingernail to reveal the connector ribbon cable which is soldered to the board. There are pretty much no connectors on the board, everything is soldered — or glued—directly to the PCB.

The front of the main board of the Long-CZ J8.

Flipping the board back over, and prying the RF shield off the back of the board with our handy metal spudger, reveals the only two pieces of silicon on the board.

The main chip is a Spreadtrum SC6531, it’s a single chip based baseband transceiver aimed squarely at the low-end feature phone market. Based around an ARM926EJ-S processor — an entry point ARM, although one still capable of running a full operating system like Linux or Symbian. It’s actually overpowered for this phone, the chip provides support for a 2MP camera. You can pick up the SC6531 on AliExpress for around $3.00 a piece in small lots.

The only two pieces of silicon on the Long-CZ J8 main board.

The other silicon present on the phone is the HunterSun HS8292U. It’s an RF chip for quad-band 2G GSM/GPRS cellular handsets at 850, 900, 1800, and 1900MHz. You can pick it up on AliExpress for under $2 a piece.

It was really interesting to compare this phone with the $12 “Gongkai” phone that Bunnie Huang picked up a few years ago at the Mingtong Digital Mall in Shenzhen. The build quality and design were pretty similar, this was just a lot smaller, showing perhaps how the technology stack has matured over the last couple of years.

The Long-CZ J8 itself can be picked up on AliExpress for around $20—about half the price its selling for on Amazon—and I’m fairly sure it’s available for much less in Shenzhen, possibly around the same price as Bunnie’s “Gongkai” phone. So if you’ve seen it around in Shenzhen, I’d be interested in hearing what it’s selling for in the markets.

80 thoughts on “Tearing Down the Boss Phone






      1. Doesn’t appear to have any water/dust proofing on the phone. Maybe the next release will be IP67… or whatever the IP code is for storage in a body cavity for extended periods.

    1. Prison operators can defeat this “boss phone” by making the prison into a Faraday Cage. Just have prisoners in chain gangs coat the prison with some glue and aluminium foil and put copper screens on the windows. You can make each cell block into a Faraday cell block one at a time until you have a complete Faraday prison. In the mean time, you take the inmates caught with phones and move them into the completed Faraday cell blocks.

      If El Chapo was in a Faraday cell, he may have been slowed down.

      1. That isn’t as easy as it sounds.
        Every tiny fault, like a not completely shutting door seal, completely disables the effect.
        Everybody that ever built/maintained an EMC measurement chamber, knows that sealing a complete building is next to impossible.

        1. Easier and cheaper to simply jam the phone signals, or put up one of those fake celltowers and route it to zero and make it alert the management.
          And just put up a WiFi for the guards to skype if needed. And change the password weekly.

          Or.. simply allow phone calls by (normal) prisoners, with supplied phones that you know the number and IMSI of so you can punish misbehavior.

          1. Since Correctional Officer’s are not allowed to have their cell phones in the prison this wouldn’t be a problem to block all calls. The issue at hand is a lot of prisons are near Residential areas and what happens if you block their cell phone traffic by accident.

        2. I remember somwhere in a book I read (fiction) where a guy was kept in a faraday cage, so he couldn’t call out with his phone. At the time I thought “what if he grounded his antenne to the cage? Would it make the cage one big antenne?” Would that work?

      2. Would be very expensive to make the entire prison a Faraday cage and th cost of prisons are already high enough it bankrupts states with high incarceration rates and in the US most of the prison workers are not exactly the most technically qualified individuals on the planet and I assume in Mexico they’d be much less qualified.

    2. People use rubber envelopes for their smartphones, just to protect the sensitive glass parts of the case. In this case a little different protective rubber would probably be sufficient.

    3. Also would need to be water proof though as small as it is you could have just a small drone,pigeon, or trained rat carry it in.
      If it’s impact resistant use a sling shot to send it over the wall.

      1. As predicted, wearable tech that reminds you to do something, the peak of civilisation.
        As a side note, I quickly scrolled through the article to the comments and I swear I saw a processor with “spreadum” written on it.

        1. oh, thats certainly the end game…but you need to distract people with false claims of needing to take a shit before any of the magic happens. by the way, probably a bad idea to design it that way.

      1. In the Netherlands 2g is kind of important for connected devices in the utility infrastructure. Just last week a smart meter for electricity and gas was installed in my home gprs only. I was told the battery for the gas has a 15 year lifespan. there are estimates 3g will be shut down before 2g.

    1. They are, but China’s still churning out 2G chips for pennies in ridiculous numbers. Even though I’m pretty sure that if you smuggled something into a Chinese prison, you’d severely regret it. So they’re intended for export I think.

      I suppose when 2G dies, and there’s only a couple of networks, and a couple of virtual ones on top of those, that still support it, then the Chinese will have to start putting proper 3G chips into phones, or 4G. I dunno why they don’t now. How much more expensive can it be? You can get smartphones pretty cheap, so throwing away the screen, battery, most of the expensive parts, you must be able to get a 3G chip for cheap enough.

      It’s annoying actually, the China watch-phones are the same, most Chinese unusual-type phones use shitty 2G chipsets, often the Mediatek, I think 6326.

      1. All that 2G infrastructure would be boxed up and sold off to 3rd World network providers and so that would be the market the Chinese have in mind which is also why the device is so cheap.

        1. I suppose, but it hasn’t happened yet. Why make them now? It’ll always be cheaper tomorrow.

          More importantly, why no 3G version? Is 3G really that much harder to put in silicon? I know 4G uses some really weird, cutting-edge tricks, that may well need a lot of maths. 3G I dunno but you can get 3G modems in USB sticks for not too much money.

    2. 2G is the data connectivity, so it should still work as a plain old mobile phone.
      It just won’t be able to send/receive SMS or connect to the internet, if there is no 2G network avaiable.

      1. SMS is not related to internet/data access. It is part of/uses the the internal signalling system of the phone network. SMS was there long before anybody thought about mobile internet access and it is one of the most reliable mobile services. Often you can transmit an SMS even when no voice call is possible because of a very weal signal reception or very high network load. Therefore if you can talk you sure can send SMS.

      2. No, the cheap Chinese (in my case, watch-) phones won’t work with a SIM from a 3G-only network. They need one that supports legacy 2G protocol. For voice calls, for everything. They won’t even log on to a 3G network.

        My watch phone is mostly intended (by me) to be used as a Bluetooth accessory to my normal smartphone, so it doesn’t really matter if it doesn’t work independently. And it was 17 quid so who can complain? But it’d still be nice if it supported modern networks.

    1. I think these would probably fit up your pooper more comfortably.

      There is a video on Youtube of some silly bastard selling these on a market stall, demonstrating by wrapping one in a condom and swallowing it. I really hope the guy can regurgitate at will, because that’s not gonna go through all the pipes too well. Daft twat’ll end up in hospital, and if he’s not lucky his stomach acid will eat into the battery, then he’s good ‘n’ fucked.

      1. This watch phone I got here was first purchased by your great-grandfather during the first World War. It was bought in a little general store in Knoxville, Tennessee. Made by the first company to ever make watch phones. Up till then people just carried pocket phones. It was bought by private Doughboy Ernie Coolidge on the day he set sail for Paris. It was your great-grandfather’s war phone and he wore it every day he was in that war. When he had done his duty, he went home to your great-grandmother, took the watch phone off, put it an old coffee can, and in that can it stayed until your granddad Dane Coolidge was called upon by his country to go overseas and fight the Germans once again. This time they called it World War II. Your great-grandfather gave this watch phone to your granddad for good luck. Unfortunately, Dane’s luck wasn’t as good as his old man’s. Dane was a Marine and he was killed, along with the other Marines at the battle of Wake Island. Your granddad was facing death, he knew it. None of those boys had any illusions about ever leaving that island alive. So three days before the Japanese took the island, your granddad asked a gunner on an Air Force transport name of Winocki, a man he had never met before in his life, to deliver to his infant son, who he’d never seen in the flesh, his gold watch phone. Three days later, your granddad was dead. But Winocki kept his word. After the war was over, he paid a visit to your grandmother, delivering to your infant father, his dad’s gold watch phone. This watch phone.

        This watch phone was on your daddy’s wrist when he was shot down over Hanoi. He was captured, put in a Vietnamese prison camp. He knew if the gooks ever saw the watch phone it’d be confiscated, taken away. The way your dad looked at it, that watch phone was your birthright. He’d be damned if any slopes were gonna put their greasy yella hands on his boy’s birthright. So he hid it in the one place he knew he could hide something. His ass. Five long years, he wore this watch phone up his ass. Then he died of dysentery, he gave me the watch phone. I hid this uncomfortable hunk of metal up my ass two years. Then, after seven years, I was sent home to my family. And now, little man, I give the watch phone to you.

  1. This, on the same day I get an email from instructables entitled “12 unusual uses for vaseline”.
    and I thought prisoners were too busy building computers to be ringing people up.

  2. “It’s hard to get across how small this phone is, at 68mm×23mm×11mm it’s about the size of my thumb, and it weighs just 18g.”

    How do you dial your thumb?

  3. If only 2G phone or data still worked in the USA… it was phased out by att end of last year. I had a couple phones I really liked that are useless now… bummer

  4. For this feature the BM50 is worth its $16 value, you can change the IMEI on the fly which when paired with a new SIM card should get it unblocked even if the prison or gubmint sniffs a previous SIM/IMEI combo.
    *#06# to read the BM50’s IMEI (Star,hash,zero,six,hash)
    *#016# to write new IMEI to BM50 (star,hash,zero,one,six,hash)
    I have hacked a phone’s IMEI with a cable before just for fun as I had the sim unlocker program and saw it also had that function, but this is one of the few fully eye patched, hook handed, peg legged, swashbuckling pirate phones with the IMEI hack ready to go on the keypad along with the size, stealth, and somewhat goofy voice changer.
    Fortunately I don’t need the fits your prison pocket size at least for that reason, but for novelty it is up there with a set of lock picks, and is a cool way to have an emergency phone if your battery dies or you dunk your big phone in a pool.

    1. Sorry I missed a digit,
      *#0160# to write new IMEI number
      Star, hash, zero, one, six, zero, hash
      I just realized that if you keep a safety pin rubber banded to your BM50 you also have that cool reset hole to quick wipe saved phone numbers and SMSs.

    2. Tried plugging one in to charge, it has a 53Mb RW mass storage partition which comes up on USB. Has an APK to use the little phone as a dialing pad for a tethered phone in your pocket two other files as well as a tiny bit of extra space which you can use for something else.

  5. I came up with a variant of this that “WEEEcycles” old 3G dongles.
    Plus if the authorities try and retaliate by blocking GSM thus rendering the mini phones worthless the dongles just compensate by rerouting signals and can even show if active or passive jamming is being used.
    Interestingly my intended application is radiation monitoring and it works fairly well for this.
    I did some more analysis and it seems that the chips may in fact be leftover stock from 3G/2G dongle manufacture on some
    older units.

  6. Um.. you would have to find a connector. I actually hacked together a DIY charger that works through the headphone output, all you need is a pair of Schottky diodes.
    Ideally you want 150mV ones but it does work remarkably well even from a second device like MP3 player or TV with headphone output. Patent pending!

  7. Note: the FM IC can be useful in itself.
    I’ve looked into whether I can use a modified image to enable features like the camera input as the pads are actually there. The camera used on the original Pi Zero (uses 47uF input capacitor incidentally) is very similar and you can also substitute any compatible IC with similar pinout.

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