I haven't google it yet, and I'm probably asking for something that has many answers. However I would like to use our community feedback with an Elastix point of view. I'm looking for a simple way to transmit and receive on/off TTL signals to trigger context/asterisk actions. The electronic part of it does not seem to be a big issue (I remember soldering years ago on the motherboard of my Apple II+ to detect inbound phone calls and to pulse dial from an visicalc spreadsheet list of numbers...) Is there out there simple boards to do it? Should I find a USB parallel port for that (if there are some compatible with Centos)? Should I play with serial ports? I can even go for an overkill with a ucontroller in between to buffer it. But my linux knowledge is quite inexistent. Then what would be the proper way to start a script when an I/O is triggered and what script should I use to change the status of these I/O?