Do a web search for 'GPS Tracker', this device has a GPS receiver and cell phone circuitry that requires a normal cell phone SIM card to be installed, it will also have a rechargeable battery in it. This device can be called from a cell phone and when the unit receives this call it will send a text message back to the calling cell phone with it's position co-ordinates, they can also be programmed to automatically sent their position at a regular time interval, this position can be directly displayed on a smart-phone map. I don't think you will be able to place this device inside a trail camera because there won't be enough room, also some (not all), of these devices can cost more than a trail camera, although I have also seen them on Ebay for £20 - £40 U.K.