The software system, developed by Brazilian researchers, has a dashboard camera that issues a warning to drivers when they raise their mobile phone to their ear.
The camera detects a driver's face and the area around it, 'The Times' reported.
The software, developed by scientists at Santa Catarina State University in Joacaba, identifies skin areas and determines whether they represent a face alone, or a face with a hand next to it - a tell-tale sign that the driver is making a phone call.
If the software thinks that there is a hand next to the face, it will give the driver a warning.
The system could be used by car hire companies and parents worried about their children making calls while driving.