New roadside detectors catch drivers on phones
New roadside detectors are being trialled which can tell if drivers are on the phone.
The sensor devices are not used to fine people at present but could eventually catch out motorists in a similar way to speed cameras.
It is already illegal to hold a phone while driving but the new system can also detect if a passenger in the car is making a call.
And manufacturers Westcotec do not think it will be long before they will have the technology to tell if a driver is on a hands-free device or not.
Westcotec technical engineer Olly Samways said: "I think it will take five to ten years because technology is advancing so quickly at the moment.
"We've just got to keep our heads down and keep working at it. I think there's definitely a solution in the long run."
The signs are only being used in Norwich to start with to test their effectiveness.
But for the moment they are just a warning that driving on the phone can be dangerous.