The three month warning period is over for motorists who get caught by mobile phone detection cameras across NSW, and be warned the fines are hefty.

From this Sunday, March 1, the penalty is five demerit points and a $344 fine ($457 in a school zone), and if you get caught during a double-demerit period you'll cop 10 demerit points.

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The cameras will be a mix of fixed and relocatable devices and they will be used across the state.

NSW Police Assistant Commissioner and Commander Traffic and Highway Patrol Command, Michael Corboy, said people need to be accountable for unsafe driving practices.

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"Distracted driving and any activity that diverts attention from driving, including talking or texting on your phone, eating and drinking, talking to people in your vehicle, fiddling with the stereo, entertainment or navigation system-anything that takes your attention away from the task of safe driving," he said.

"The reality is they are not only putting the lives of themselves and their passengers at risk but also others travelling on NSW roads."

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The cameras come following a six-month trial in Sydney that checked 8.5 million vehicles and caught 100,000 drivers illegally using their mobile phone.

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