I once read a nice piece of work by a kid in the UK who designed a device that "sniffed" the same ID/RF code that the wireless sensors would give and record them to computer. Im not sure what he used to do the actual frequency snooping, but what i found intersting was the way he figured out to render the sensor useless. As i am aware from what my father told me about his DSC system, when a sensor's battery is about to fail it sends a message to the main router where all the information is taken in and processed. The guy would actually sit by a sensor and a sniff out multiple signals and feed them into a program that would find a replicate of the algorythm that the router was expecting from the wireless device. It would them send out a battey fault message, causing the system to accept the second replicate algorythm as the new one. Im not sure if I got all the data right, but it seemed to me like he had figured out a way to the systems core programming. Im not very familiar with security systems, but is it true that when a battery is replaced in a wirless device, there is a "pairing" function to assosciate with that device again? Something much like a wireless mouse with a computer. It seemed like a sound idea to me, and I know that my security system at home seems to have many issues with the way wirless sensors interact with the router. I even remember once when i was 16 I had created a spread spectrum device for my stereo that used 2.4ghz to stream music. I was calibrating it at around 1 o'clock when it set off all of the wireless sensors in our house. Long story short, it caused the police to come to our house with a report of Glass Break from DSC. Im not sure if that specific code came from a certain frequency during calibration, or what.