Fewer drivers received penalty notices for using phones in Dyfed and Powys last year, new figures show.
According to the Government, a change in the law may be behind a 33% rise in the number of fixed penalty notices given to drivers using their phones across England.
The RAC has also suggested young people may be more likely to be using devices while behind the wheel.
Figures show Dyfed-Powys Police handed out 69 notices for the offence in 2023, down from 168 the year before.
Last year 41 led to a fine, while the remaining 28 resulted in a court summons.
These figures do not include FPNs ultimately cancelled by the force.
A law change has broadened the definition of phone use – meaning the offence is now triggered whenever someone holds or interacts with their device.
The Home Office has cited the change as the reason for 9,000 more offences being logged in 2023, with 36,800 FPNs issued outside of London.
The Met Police – which covers London and accounts for a large portion of driving offences – uses a different system and its figures are not included in national totals.
The RAC, a motorists' association, highlighted a "concerning" rise in young people using phones behind the wheel, based on a national survey of drivers.
Its research suggests 39% of drivers aged 17 to 24 had checked texts or emails while driving, and 30% had taken a photo or recorded a video.
Rod Dennis, the organisation's road safety spokesman, said: "Anyone who uses a mobile phone at the wheel in any way is not just risking their own lives, but those of their passengers and all other road users."
"The only ‘screentime’ drivers should have in the car is looking through the windscreen as they focus on the road," he added.
He welcomed the introduction of AI-assisted cameras which he said will better allow police to identify people breaking the law.
Drivers can receive six penalty points and a £200 fine if they are caught using a phone while driving.
Dyfed-Powys Police handed out a total of 2,037 driving-related FPNs last year, excluding cancelled notices. This included 450 offences for speeding and 105 for not wearing a seatbelt.
A Home Office spokesperson said: "Using a phone while driving is a serious distraction that risks the lives of drivers and other road users.
"While enforcement is a matter for the police, there are tough laws in place to clamp down on phone use behind the wheel, and the Government is committed to reducing the numbers of those killed and injured on our roads."