The move comes amid increasing concerns over the risks posed by drivers using mobile phones at the wheel.
The road signs work by using a scanner to detect the radio signals emitted when someone in the vehicle is connected to a call, with this data used to illuminate a sign further down the road.
Norfolk County Council's Road Safety team have been working in partnership with Westcotec, a vehicle sign technology company, to develop the and deploy the new mobile phone detection system for use on the county's roads.
It is able to detect bluetooth signals so that anyone who is legally using hands-free calling will not be wrongly issued a warning.
Holding a phone while driving was outlawed in the United Kingdom in 2003 but 23% of people admitted to taking a call in last year's RAC Report on Motoring.
The first of three £6,000 electronic signs was yesterday introduced in Norwich, Norfolk.
Although the technology can not record specific number plates, data generated from the system, including the number of activations and the times of day they take place, will be shared with Norfolk police who might then use it to set up future crackdowns.
For the first time sensors will be installed on British roads that can detect when a mobile phone is being used in a vehicle and present drivers with a warning sign.
Statistics from the devices will be shared with Norfolk Police, the county council said.
Chris Spinks, of Westcotec the firm behind it and former head of roads policing in Norfolk, said: "So many people, by force of habit, can't resist using their phone".
Inspector Jonathan Chapman, of the Norfolk roads policing unit, added: "This scheme is a good example of how we can work with local authorities to make using a mobile phone whilst driving as socially unacceptable as drink or drug-driving".
"Whilst this is still not a flawless science, the new generation of sign is significantly more accurate and reliable than the first". Using a mobile phone at the wheel is one of the fatal four road offences which can have devastating consequences if it causes a fatal or serious collision.
The system will initially be used at sites in Attleborough, Holt, Norwich and Toftwood.