System and methods are described to track and warn a person suspected of texting while driving, or alternately to block texting for drivers of moving vehicles. The position and speed of cell phones, and a GPS-enabled telematics system if present, are compared with those of other GPS-enabled devices in the vicinity. If the position and speed of a phone track that of one or more neighboring phones or a telematics system, it is assumed that a cell phone user may under certain conditions be texting while driving. For circumstances where persons suspected to be in the same vehicle utilize different service providers, parameters such any of cell phone position, velocity, and direction of travel are time-stamped and then compared. Texting is detected emanating directly from cell phones, or from a telematics system in a vehicle, or via a WiFi hotspot of a cell phone in the vehicle.