A different kind of phone hacking

I previously mentioned this awesome project to rip out the innards of an old rotary dial phone, and stuffing a Raspberry Pi inside which plays a different MP3 file out of the earpiece each time you dial a different number.

I decided to have a go myself, having found 2 old phones in the loft. These are old British Post Office / GPO phones, so the wiring is probably different. I’d also like to keep these phones intact if I can, so I decided to do a bit of probing to see if I could attach a RaspberryPi to the phone’s existing internal terminals.

First – I had to choose a phone. The red one is type 706, the white a newer type 746.

I soon plumped for the white one as its terminals were more accessible and there’s more room inside.

The red one has an extra button and even has a vertical early PCB ‘card’ inside. Following the wires round inside is a nightmare, so I put this one back together and let it be.

I started probing – appropriately – with an old British Telecom multimeter, which was fine for locating the wires for the receiver ‘hook’ (it might be nice to have a dial tone when you lift the handset!), but a multimeter doesn’t react quickly enough to count pulses from the rotary dial. So I made a simple circuit with an LED to test the different terminals inside the phone to see if any were connected across the dial switches – and indeed they were. By breaking the LED circuit, and touching the loose ends across different pairs of terminals and dialling, I could see when the light flickered, showing the dial breaking the circuit to transmit the numbers.

Modern fixed phones dial by sending tones down the line to the exchange – known as DTMF or TouchTone. Old rotary phones worked by breaking a circuit to the exchange creating pulses at a rate of 10 pulses per second. 1 break in a second means you’ve dialed 1, 2 breaks is a 2 and so on. But what about 0?

I’m might confused by the wiring instructions in the original article, so next steps are to look carefully at the code, and perhaps write my own. And buy a jack plug so I don’t have to solder the earpiece on to the Pi direct.

Thanks to my former colleague Frank Bath for information about Strowger telephone dialling, and to James West for reminding me about phone phreaking and an old way you could sometimes cheat a payphone in the UK by tapping the cradle switches to mimic the dial pulses. I used to actually phone people this way on my home phone. Hey, I didn’t get out much, and phone numbers in my village were 4 (FOUR) digits long. And I can still remember my friends’ numbers: 2235 and 3516. And no, they’re not my PINs…

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2 cool RaspberryPi projects

Here are two insanely cool Raspberry Pi projects I spotted this week.

First up, turn a rotary dial phone into an MP3 player. This seems really simple and do-able. James West points out that some telephone EQ on the audio files would be desirable – boost the mid, slice off the top & bottom. The example plays nursery rhymes, and I can see this being a great gizmo to have in a classroom for KS1 children. Personally, I’m tempted to make a modern day Dial-a-Disc phone for my daughter. And if you want to know what Dial-a-Disc was, ask your gran.

Next: Libby Miller does very cool things with Raspberry Pi radios. (I think she may get paid for doing this, in which case she totes has my dream job). For some reason I’ve only just stumbled upon Radiodan, and I’ll be experimenting with this radio prototyping platform as much as my time allows. I love making RaspberryPi radios, and this is so much up my street I can’t believe I didn’t know about this – or perhaps I did and it got lost in the noise. Anyway, Libby’s latest radio uses old Oyster cards to play different podcasts when you present the relevant card to the radio. Wave Mark Kermode at the radio – Wittertainment! Sarah Koenig – get Serial! Totes amaze.

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Review of the Year – only kidding

I hate New Year’s Eve, I hate looking back at the last 12 months and I hate making resolutions. Especially when years suck as much at 2014 did. I won’t bore you with the details, but it included death & unemployment as well as the usual ‘I don’t know what to do with my life’ (© Buzzcocks) ennui. But I did learn a few things over the Christmas holidays:

  • I only saw ONE film from Wittertainment’s Top 10 Movies of 2014 – and I really didn’t like it one bit (Imitation Game, since you ask. Watch Enigma instead. More entertaining and probably more realistic despite being fiction). But I did re-discover three old films that are probably in my all-time top 10 films, thanks to Christmas TV.

  • The Ipcress File is as cool, grubby and fresh as I remember it. Every bar of John Barry’s amazing score is a different Portishead song. Michael Caine cooking with eggs is a great moment in cinema, and reminds me to make more use of Len Deighton’s Action Cook Book.
  • Channel 4 showed a lovely crisp print of Bugsy Malone. The songs are brilliant, it never loses its appeal, and there’s Jody Foster taking a custard pie in the face saying ‘so this is showbusiness?’ After me: we could have been anything that we wanted to be…
  • Hitchcock’s 1935 film of The 39 Steps is a masterpiece. I hadn’t seen it for, well, decades probably. It has aged incredibly well, it’s funny, entertaining, sexy and Robert Donat is just superb. If you’re tempted to think that screen acting wasn’t up to much in the olden days, watch him in this and marvel.
  • Away from the screen, having a puppy has been fun – if at times like having a 4th child in the house. I have learnt which fellow dogs (and owners) to trust and met some lovely people in the park. Now if dog-less people will just stop taking shortcuts through the dog exercise area and getting arsey with me when my dog greets them…
  • The MEATLiquor Chronicles is an infuriating, but brilliant book. After reading it I felt simultaneously hung-over, thirsty, sick and hungry. I soon learned to skip the DBC Pierre twaddly bits and seek out the gems. There aren’t a huge number of useful recipes in this book, but I think you only ever get 3 really useful ones out of most cook books any way, and this book contains some fantastic ones. The Red Snapper has now supplanted the Bloody Mary as my favourite drink, and the Layer Chilli recipe is, hands down, the most delicious thing I have ever made. I halved the cooking time and stock content and it was still amazing, served over nachos and melted cheese to replicate the divine chilli cheese fries we love at MEATMarket so much.
  • I discovered a great set of stories by G K Chesterton: seek out The Club of Queer Trades. Quite why Mark Gatiss hasn’t adapted this for the BBC is beyond me. And I re-read a childhood favourite, The Owl Service by Alan Garner. As good as ever, and it inspired me to get writing fiction again.
  • 2014 was a blank year for music for me – I think I only bought 2 albums. But I did discover, very late in the day, that I still have the capacity to be so moved by my enjoyment of a song I stumble across that I can be moved to tears, even if I don’t know why:
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My Christmas gift to you

Here’s my Christmas gift to you – a short story inspired by two of my favourite books. You can also download it in .mobi format for Kindle, or .ePub for other devices. Merry Christmas!

No Service
A Tale of Two Books
by Giles Booth

© 2014 Giles Booth, all rights reserved.
Giles Booth asserts his moral right to be identified as the author of this book.

With acknowledgements to the great Alan Garner and Shirley Hughes.

‘Worst. Christmas. Ever.’
‘Don’t start, Lucy,’ said dad softly from the driver’s seat.
‘Could be worse… they could be saying “are we there yet?” every five minutes.’
‘The only reason we’re not saying that is because we don’t want to get there at all,’ hissed Tom.
It’s fair to say that there’s no love lost between Tom and Delyth. Delyth is dad’s girlfriend. I was going to say new girlfriend, but as he’d been seeing her for about a year before he left mum, I don’t think she counts as that new. I’m not keen on her either, mind, but I’m not like Tom. He’s either silent or vicious to her, nothing in between. He hates her and I think he hates dad now too.
‘Tom, please don’t speak like that. I know this Christmas is going to be… tough. Let’s try and make the best of…’
‘A bad job?’ snapped Delyth, clicking on her phone.
‘That’s not what I meant…’ stuttered dad.
Delyth scanned her phone. ‘I could be out with me mates now. The book club are going on a pub crawl tonight followed by the theatre. It’s my work Christmas party. My best friend for college is over from the US, I could be having cocktails with her. But no, I’ve been stuck in a car with you and your… children for the last six sodding hours.’
‘It’s not my fault about the traffic on the M4. And anyway. It was your idea for us all to go to your family cottage in Wales…’
‘I had pictured the two of us, you know, a roaring log fire, cut off from the world. And seeing as my sister had to cancel…’
‘Again, not my fault.’
‘No. Your bloody wife’s fault. Dropping everything. Taking off like that.’
‘She’s… still upset.’
‘If you hadn’t paid for it, she couldn’t have gone. Guilty conscience.’
‘Of course I feel bad. She’s always wanted to go to Savannah. I wasn’t going to stop her, in the circumstances.’
‘Christ,’ whispered Delyth, furiously tapping at her phone.
I guess I felt a bit sorry for dad. He and mum had sat us down and explained to us that they weren’t getting on (like we needed telling) and how they both had had enough of the rows, they had decided it was best for everyone if he left. But I couldn’t see what had changed. He used to argue all the time with mum, and now he was constantly bickering with his girlfriend. What had it achieved, apart from making mum so sad she hardly ever stopped crying? And drinking.
Tom put his headphones back on and I could hear fuzzy guitar music leaking out. Delyth’s face was lit by the glow of her iPhone, dad’s by the faint green luminescence of the dashboard, It was utterly dark outside, hardly any other cars on the road, weird after the interminable traffic jams getting out of London, the odd sense of looming hills in the distance. Silence in the car. Silence so painful I wanted to scream.
Tom fell asleep, and so did Delyth. I waited. And waited.
‘Are we there yet?’
I saw Dad smile at me in the rear view mirror.


It was gone midnight when we got to the cottage, and so dark I didn’t take in what the place was really like. I just remember dad bundling us into the house, telling Delyth to leave all the food except the wine and it being so, so cold. I fell asleep curled up in a sleeping back on top of an old bed in a room slightly bigger than the one I had at home.
I woke up utterly disorientated. My phone said 8.37. No signal. I badly needed a pee. I had no idea where the bathroom was. Mum always used to joke about that. ‘They never need the loo in films and stories, do they?’ I wondered where she was now, if someone was looking after her, of if she was still crying into a drink in a departure lounge somewhere. Maybe a rich, handsome American would take pity on her and whisk her away. Or maybe someone would break her heart again.
I staggered along the landing and opened the first door. It was a dark box room and at first I thought it was empty, but I then I saw Tom. Well, I smelled him before I saw him. Fifteen year old boy smell. Rank.
I tiptoed downstairs and into the living room. There were embers from a dying fire and two empty wine bottles. Dad and Delyth were asleep on the sofa in each other’s arms. So I suppose they must have made up. I crept into the tiny kitchen and found a wooden door with a latch opening off it. Toilet! Bliss. It was so fricking cold, though. Even colder than the kitchen, I thought my feet were going to freeze to the rough concrete floor. I couldn’t decide if the glass in the window was frosted or frozen, so I ran my hand over it. Turned out it was both. A line of sugary ice outlined my fingers. I pulled the chain, and nothing happened. Great. Steam rose from the bowl.
Worst. Christmas. Ever.


‘You coming out for a walk?’ asked dad, startling me as he stuck his head round my bedroom door.
‘I fell back to sleep.’
‘So’s Tom. Can’t rouse him. Come for a walk with me and Delyth. Blow away some cobwebs.’
‘No I’m all right. You go.’
‘There’s bread on the kitchen table, and some eggs and bacon in the fridge if you fancy a fry-up. The smell might wake Tom up.’
‘Ok dad.’
I heard him go back downstairs and some low muttering between him and Delyth. I leant over to the window and pulled the curtain to one side. The glass was iced up in here too. I rubbed at it and saw dad kiss Delyth on the lips and lift her off her feet slightly. She wrapped her arms round him. She looked tiny, even in her chunky walking boots and thick clothes. Not much bigger than me. I had no idea what he saw in her. She wasn’t even pretty.
They walked off hand-in-hand. I wondered where they were going. All I could see was the steep valley side opposite, and low, dark clouds. Aside from the distant sound of running water, it was utterly silent.
My phone said it was nearly midday, but it seemed to be going dark already. Still no signal. No TV, no wifi and no phone signal. Couldn’t even send a distress text to Nan or Edie. Edie’s my best friend. Her parents split up last year, but it wasn’t like this. Far more normal. She did have to move house, though. I suppose I’m lucky on that score.
I lay on my bed staring at the ceiling. What was I going to do for a whole week of the holidays, stuck in this dump? Not even the middle of nowhere, this was way outside nowhere, beyond the suburbs of Nowheresville, the back and beyond of Zilch. I had a pile of books on the bedside table that I was supposed to read: secondary school reading list plus a couple that Delyth had bought me. I flicked through a couple of them. I Capture the Castle. Something by Alan Garner, inscribed ‘to Lucy, these books meant a lot to me when I was a teenager, I hope you grow to love them too.’ Yeah, grow to love me, more like. She’s an English teacher. Not at the school I’m going to, thank god. That would be unbearable.
I’d also brought my comfort books. I have a stash of books, mostly Christmas ones, that I bundle up in bed at this time of year. They’re like a security blanket, picture books and story books I’ve had as long as I can remember. They remind me of when dad had time to sit and read to me every night and Tom would stand in the doorway thinking we didn’t know he was there, listening. Lucy and Tom’s Christmas was my favourite. Not just because of the names, but the familiar comfort of a happy family, the safety of knowing that the story would unfold in exactly the same way every single time I read it. They would never decorate the tree until Christmas Eve. Mum and dad would be asleep when the children awoke. Tom would always get over-tired in the evening and go for a walk with grand dad.
I suppose I must have started to drift off again when I heard something. Like a scratching noise. Coming from the ceiling. Getting louder. It was really dark now and I fumbled for the light switch on the bedside lamp. It fell over and the bulb shattered. ‘Shit!’ I cried. Then felt bad for swearing.
No answer. Scratching again. Scurrying across the ceiling, Must be mice.
Silence. Then the noise again, seeming to come from every corner of the ceiling at once.
I jumped up in the bed as Tom came in and turned the main light on.
‘I heard noises.’
‘Like what?’
‘Scratching. In the roof.’
‘Your imagination, Luce. Reading too many spooky books.’
‘No, it’s real. Listen!’
‘What on earth have you done to the lamp?’
‘It fell over.’
‘Stop it!’
The scratching noise came again, louder and deeper.
‘Do you think it’s mice, Tom?’
‘Bloody big mice. Rats more like. Or squirrels. I wonder if we can get up there…’
‘There’s a loft hatch in the corner.’
‘So there is. I think I saw some stairs as well, though. Come on, let’s investigate.’
Out on the landing between our two rooms there was a white door that I’d hardly noticed, covered with the same kind of wood panelling as the walls. The latch was stiff and Tom had to bash it hard to open it. Inside was a narrow staircase, so dim we could hardly find our feet as we ascended.
‘Locked,’ said Tom as he tried the handle.
‘Probably just as well.’
‘I can’t see anything through the keyhole either. It’s like there’s a key on the inside.’
‘That’s impossible.’
‘Impossible – unless there’s someone in there,’ Tom whispered in a ghoulish voice.
‘STOP. IT. NOW!’ I yelled, running back to my room.
Tom followed me and pulled an old dresser across the floor so it lined up with the loft hatch.
‘You’re not going up there.’
‘Yes I am.’
‘That thing’s on its last legs, it’ll never hold your weight. You’ll fall and I can’t call an ambulance, there’s no phone here and no mobile signal and…’
‘Hush, sis. Hush.’
The scrabbling noise came again, seeming to circle the area around the loft hatch. Tom jumped up and pulled the bolt. The door didn’t budge. He banged on it three times. The scrabbling stopped and then came back, almost repeating the rhythm of Tom’s fists.
‘What the…?’
‘Tom, get down. I really don’t like this.’
‘It doesn’t open downwards, so maybe it folds up.’
Tom shoved the hatch and it moved a fraction. Dust fell down and he started to cough.
‘I think there’s something on top of the door. If I can push it harder, I might be able to dislodge it…’
He gave it a huge shove. There was a sliding noise and an almighty crash, like breaking glass.
The hatch flung open and Tom lifted himself inside.
‘Well, I don’t see any rats…’
‘What is there? Tom?’
‘Come and look for yourself.’
His disembodied arm appeared and pulled me up. In the twilight I could make out a tiny attic room with an old iron bedstead in one corner. Shapes fluttered and flickered round the room. I screamed.
Tom turned the light on.
‘Only paper, Luce. Calm yourself.’
He was right. The room was filled with paper cutouts, pinned up, some folded and standing up on their own. They were faded, yellow and curling, cobwebs appearing to support their fragile forms.
‘Owls,’ I said.
‘More likely squirrels. I probably frightened them away.’
‘No, the paper. They’re owls. Made out of flowers. Look closely, there are pencil patterns.’
‘Oh my god, you’re right. I’d never have seen that.’
‘I’ve seen this design before. In a book, a book Delyth got me.’
‘Don’t mention her.’
‘Kind of hard not to. And this is her house.’
Tom was examining the large tea chest that had been covering the loft hatch.
‘What’s inside?’
‘Crockery. Or was. I think I broke most of it.’
He pulled out some shards of a white plate with a green and gold pattern.
‘Shit, Tom, we’re going to get into trouble.’
‘Let’s just put everything back where it was. They’ll never know we were up here.’
‘But we can’t.’
‘Why not?’
‘God Tom, are all boys born stupid?’
I pointed to the door. ‘The room is locked on the inside. There’s no-one in here, looks like there hasn’t been anyone in here for years. And the crate of crockery was covering the hatch.’
‘Oh my god. So how did anyone get out of here? Oooh, Luce, this is a real locked room mystery!’
‘Let’s get out of here before dad and Delyth get back.’
‘Where are they?’
‘They said they were going for a walk.’
‘It’s pitch black out there. Maybe they went to the pub.’
‘Delyth said the nearest pub was five miles away.’
‘Perhaps they fell into a ditch and she drowned.’
‘Sorry. Can’t say I’d be sorry though. Like you said, would be a nightmare getting an ambulance out here.’
‘I think I can hear someone!’
The front door slammed and I could hear dad calling.
Tom closed the hatch and between us we dragged the tea chest back to where we assumed it must have been. I grabbed the key from the door and we tiptoed out, locking the door on the outside. We crept back to our respective rooms.
‘Lucy! Tom! We’re back! Do you fancy some stew for dinner? Or pizza?’
‘Whatever, dad,’ I yelled.
He burst into my room. I could smell the fresh winter air on his clothes. And Delyth’s pungent perfume on his skin. Mum said it was ‘cheap scent’.
‘How’s my Lucy-Goosey?’
‘Sorry. Been up to much?’ he asked, sitting on the bed.
‘Oh yeah, loads, I’ve been watching TV, Tom’s been on the XBox, I Facetimed my mates… oh, no, hang on…’
‘Look, it’s good for us all to be away from gadgets for a week. Unwind. Reconnect with nature… and each other.’
‘It’s so unfair. There’s no phone signal at all. I can’t even text Edie. Or mum. Have you heard from her?’
‘No, my phone’s not working either. We’ll go to the pub for lunch tomorrow, I’m sure one of our phones will work in the village.’
Dad ruffled my hair and kissed the top of my head.
‘What happened to the light?’
‘I knocked it over. Sorry.’
‘I’ll clear that up. Broken glass is dangerous.’
The shards of the bulb were strewn all over Lucy and Tom at Christmas. Dad brushed them aside and started flicking through the book.
‘Good lord. I still remember the day I bought you this book. Must be 10 years ago now. Burst out laughing when I saw the title, bookseller thought I was daft…’
‘Will you read it to me dad?’
‘Aren’t you a bit old for a bedtime story?’
‘No. Never.’
He turned back to the first page and was about to start reading when the bedroom door flung open. It was Delyth. The moment was ruined. I could have killed her.
‘Do you want a glass of wine?’
‘Yes. Thank you, darling, in a moment. I’m just…’
‘What’s that dresser doing in the middle of the floor? My god, it’s covered in dust. And why’s the lamp broken? What on earth have you been doing in here?’
I couldn’t tell if she was flushed with anger or the cold, but it sounded like the former.
‘I heard a noise, got scared…’
‘Yes well, young lady, this is not your house, this is my family’s house, and you need to treat it with a little more respect…’
‘I’m sure Lucy didn’t mean any harm, it was an accident.’
Delyth shoved the dresser but it caught on a loose floorboard.
‘Don’t just sit there. Come and help me!’
Dad looked utterly helpless.
‘For god’s sake!’ she hissed and gave the dresser an almighty shove, lifting it off its feet. The force caused it drop back to the floor with a bang.
At which point the loft hatch opened.
It seemed like it took hours to happen. The door fell out of the opening and slowly, as if supported by a parachute, the crate of crockery descended, Delyth all the time glaring at my father with eyes filled with hatred. Dad and I were both paralysed. I swear to god I tried to call out, but I couldn’t. I was frozen in time.
I think it’s fair to say that she never knew what hit her.
I looked at my phone.
‘No service, dad.’

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Little Box of Christmas

A good while ago, I made The Little Box of Poems. This is a box that prints a random poem every time you push a big red button. Inside is an Arduino microcontroller and a thermal till roll printer, and it inspired Carrie Ann Philbin’s Little Box of Geek. (I also made a Raspberry Pi-powered version too.)

As it’s Christmas, I’ve decided to make a seasonal version. This one prints really bad, random Christmas cracker jokes:

Here’s how to wire it up:


And here’s the Arduino code – it’s based on the Poem code, so the variables have rather odd names. If you want to find out how to add bitmap graphics, like my Christmas tree, Adafruit have a guide here. I used Photoshop and Processing to make mine.

 Little Box of Christmas
 by Giles Booth

 not for commercial use
 if you modify this code for edcuational or charitable use
 please credit Giles Booth and/or @blogmywiki in printouts

const int buttonPin = 2;     // the number of the pushbutton pin - doesn't change
int currState = 0;           // set variables to hold the state of the button
int prevState = 0;

#include "SoftwareSerial.h"
#include "Adafruit_Thermal.h" // you need to download this and put it in your Arduino library
#include "tree.h"              // Christmas tree picture
#include <avr/pgmspace.h>     // I have no idea what this does

int buttonState = 0;     // variable for reading the button status
int printer_RX_Pin = 5;  // This is the green printer wire
int printer_TX_Pin = 6;  // This is the yellow printer wire

Adafruit_Thermal printer(printer_RX_Pin, printer_TX_Pin);

void setup() {
  pinMode(buttonPin, INPUT);
  Serial.begin(19200);   // this is the baud rate of your printer - may vary
  pinMode(7, OUTPUT); digitalWrite(7, LOW);

void loop(){
  // read the state of the button:
  currState = digitalRead(buttonPin);
  if (currState != prevState)   // if something has changed, do something
  if (currState == HIGH) {
  else {
    // if you want something to happen when the button is released, put it here
    // such as a beep, or a display saying 'your poem is on its way'
prevState = currState;

void printPoem(){

  // put greetings here  
  char* myTitles[]={"Merry Christmas!","Happy Christmas!","Season's Greetings!","Joyeux Noel!","feliz navidad!","God jul!"};
  // put 1st lines of joke in here
  // they must all be on the same line, in double quotes, separated by commas
  // use \n for a new line and \" to escape a quotation mark
  char* myPoems[]={"What does Santa suffer from\nif he gets stuck in a chimney?", "What kind of motorbike does\nSanta ride?", "Who delivers presents\nto cats?",
"What never eats\nat Christmas?", "What's brown and sneaks\nround the kitchen?","What do you get if you eat\nChristmas decorations?"};

  // put punchlines here in order
  char* myAuthors[]={"Claustrophobia!","A Holly Davidson!","Santa Paws!","Turkeys - they're\nusually stuffed!","Mince spies!","Tinselitis!"};

  int poemChoice = random(7);  // choose a random poem number between 0 and 6


  printer.printBitmap(tree_width, tree_height, tree_data);    // print Blog My Wiki logo    
  printer.println("The Little Box of Christmas");
  printer.setSize('S');     // Setting the size adds a linefeed
  delay(2000);   // 2 second pause to help prevent multiple presses     
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