Make your own Tonepad for Phone Box phreaking
ELEKTRIX Issue 1 - Part 4
The Technique
Some weeks ago free dialling with tonepads came to the news in a daily newspaper. Since then there has been much in the way of media hype covering these devices in computer magazines and hackers files. This file will, I hope, make the whole practise clear and the method easy and also less costly than previously.
The way it works is as follows: The technique will ONLY work from phone boxes contrary to what you may have been told. You may also find that it is not working on some London phone boxes - this is due to the fact that many have been modified to disallow phreakers from using the method.
The technique relies on the fact that dialling 999 on a phone box automatically disconnects the charging mechanism whilst the call is being made. The tonepads which allow people to make free calls are just portable models of the tone-dialling telephone circuits that are in your telephones and in modern modems. The tones they generate are perfectly 'legal' and are simply used in portable units for Computerdial services (Share price indexes,etc.) for travelling businessmen and other groups who may use such services (like voice mail or whatever). All you do is the following:
- Go to a phone box.
- Dial the number you wish to connect to using the keypad.
- As soon as the phone starts ringing dial 999 on the phonebox machine as fast as possible. This will have cut the charging mechanism and you will have a free call.
* For boxes that have been modified......Simply put 10p in first then do *
* it - you won't loose your money but you will still make a free call. *
* This has to be done since they are modified so that they won't dial a *
* number (except 999/linkline 0800/government) unless money has been dep *
* osited in the machine.
Method 1
You can record the tones required to dial a number onto a tape and then play them down the telephone with a standard taperecorder. This has three main drawbacks however although it is the least costly method.
- You will need to record a different set of tones for each number. So unless you dial a few numbers repeatedly then you are going to find this method very tiresome. You'll need to have a DTMF modem/phone too.
- The phone system requires that each tone is within 1.5% of the specified frequencies. This will prove to be difficult if you don't own very good recording equipment.
- You will look very conspicuous playing around with a tape recorder in a phone box.
Despite the disadvantages it has to be remembered that this method is the cheapest option open to you.
Method 2
This involves building your own portable tonepad (unless you want to fork out ú12-50 for a Tandy one). The device is small, effective and relatively cheap.
One method is as follows:
[Battery] _______
+9V --------|6 |----<14-----123
| |----<13-----456 Numeric Keypad lines
| |----<12-----789
--------|16 |----<11-----*0#
[Speaker] S | |----<3------'||
--------|1 |----<4-------'|
| | | |----<5--------'
| --|15 7|---
| | | X [3.579545 MHz Crystal]
| | 8|---
| -------
GND TCM5087
(-Ve on battery)That way is simple to build since few components are needed...get a keypad off an old remote controller or something...or make your own from Push-to- make switches. Other methods include using two 555s to generate the tones or two 8037s (wave form gen. chips) though this is a little too expensive for my liking and only needs more complex circuitry.
If you intend to use 555s then you'll need a monostable on each 555 and the frequencies used are as follows:
* - 941 & 1209 Hz
# - 941 & 1477 Hz
0 - 941 & 1336 Hz
1 - 697 & 1209 Hz
2 - 697 & 1336 Hz
3 - 697 & 1477 Hz
4 - 770 & 1209 Hz
5 - 770 & 1306 Hz
6 - 770 & 1477 Hz
7 - 852 & 1209 Hz
8 - 852 & 1336 Hz
9 - 852 & 1477 Hz
