I am looking to build a small gps device that works cellularly. I want to be able to have tracking device called up remotely to track and send data to my phone or computer. I believe I just need a sim card to do this. Can someone point me in a good direction on what components I need. Endoacustica has a device like this but it is very expensive. Reading through here and checking things out, it seems like this place has what I need. I just don't know exactly what I need. thanks for any help you can provide.