I dare say a lot of this information is not public knowlege so that joe average doesn't try to crack the network. From what I know it is dedicated line 300 baud and encrypted with a rolling code. In some parts of Europe they also use the 'd' channel of ISDN. I would think you would have to pays lots of money and sign you life away to get the required information. Even with this information it does not mean that they are easy to crack - the encryption and rolling codes make that a little difficult. Once I pulled apart the PIN pad that was encased in epoxy resin to see what was in them. There was also a light dependent resistor that killed the encryption key stored in ram. The cpu was a 80c51 and the code didn't make much sense as it did bizzare bit manipulations.