Some hints for pager reprogramming and modifications

Almost all modern pagers are reprogrammed over a serial port. If you want to do this at home you have to pay a huge amount of money to the manufacturer of the pager for a simple levelconverter which does nothing else but convert serial ports +-12V voltage to a 0/5V level. The same can be achieved with a cheap selfmade converter circuit. Everyone with some electronics and soldering skills can do that within one hour or even less! So why not build one yourself and save up to hundreds of dollars? Here are the schematics:

The pinouts of the already tested pagers are:

1-TXD 2-RXD 3-AF 4-CHG 5-ANT 6-GND for the Bosch FME88

1-CHG 2-TXD 3-RXD 4-??? 5-GND 6-ANT for the Swissphone Memo/Joker

1-ANT 2-GND 3-AF 4-TXD 5-RXD 6-CHG for the Swissphone Quattro96

All pinouts counted from left to right when pager facing towards you, PINs to bottom. VERY IMPORTANT: For programming you need three lines: TXD, RXD and ground! Some people had problems making the interface work, and after exchanging some mails we discovered that they did not connect ground. Perhaps I did not tell this clear enough, but with this little additional explanation everything should be easy to understand, even for those of you who do not have very much experience in electronics.

Some further misunderstandings came up - "TXD" in my schematics means "connected (over the MAX232, not directly!!!) to TXD of the PC", of course it is RXD of the pager when assuming the pager is an independent serial communications device. You have to connect TXD of one unit with RXD of the other one when using RS232 communications :-) Confused? Just follow the drawing and pinout, then everything should work - connect the wires "TXD" of the adapter to those I called "TXD" at the pagers, same with "RXD".

You see, quite simple! This circuit was tested thoroughly with the Pagers Swissphone Memo (RE329), Quattro96 (RE429), Quattro 98, Bosch FME88 and Motorola Advisor. It should work with almost all kinds of pagers which use a simple three-line interface for programming. Maybe with some pagers little modifications will be necessary (resistors in the data lines, pullup or pulldown resistors) - hey, why should I do all the work? Feel free to play around with the circuit and let me know which pagers you were able to read and write!

If you want to know more about reprogramming of Motorola POCSAG/FLEX pagers follow the link to the blackcrawl archive. It can be found in my "Links section" under "English, Communications". In the archive choose "Cellular Telephone Utilities", and then "Pager".

You may have wondered how to program the Siwssphone Quattro 86 (RE229, compatible OEM-version: Bosch FME86). I`m afraid you can`t use this circuit for the Quattro - it is programmed with audio tones, and it needs a programming voltage of -12V, so the circuit diagram is completely different. Here it is! Be aware: USE THIS CIRCUIT ONLY WITH THE MENTIONED PAGERS RE229/Q86/FME85; connecting other pagers to this circuit could REALLY FUCK THEM UP SERIOUSLY!!!

The description in the PIC is in German, but everyone should understand the simple circuit without description. I did not build this interface - using a 12v Battery for programming voltage and some test leads also did their job :-) The transformer in the NF path is just for safety.

Also I got some information how to open the pager Motorola BMD to be able to receive everything being talked on the channel. After this modification it is not possible to turn the pager off, but why should do someone on standby this anyway? The former "off" positin of the switch is then used for the monitor functionality. You just have to install two jumpers in the pager. Use very thin wire for the blue jumper, otherwise you won`t be able to replace the cover properly! For the red jumper just apply carefully a blob of solder.