More than 50 Sussex drivers have been fined as motorists continue to ignore the ban on using hand-held mobile phones.
Fifty-three drivers have received a £30 fixed penalty notice and hundreds more have been warned.
The ban was introduced four months ago and Sussex Police initially adopted a lenient approach, preferring to warn and educate motorists before fining them.
Now they are stepping up enforcement and looking for repeat offenders, who face even stiffer penalties.
A Sussex Police spokesman said: "The ban is still being abused and the figures are just the tip of the iceberg.
"We see examples almost daily and motorists must realise we take this issue very seriously. More will face fines unless they change their ways."
Different police forces adopted different approaches and in Hampshire more than 150 drivers have been fined.
Holding a mobile phone in your car, even while it is stationary, became an offence on December 1.
Fines can rise to £1,000 if the matter goes to court and to £2,500 for drivers of vans, lorries, buses and coaches.
Drive carelessly or dangerously when using a phone and the penalties include disqualification, a large fine and up to two years in prison.
Ministers are talking about increasing the penalty by making it subject to three penalty points and a £60 fixed fine.
The only exemption to the rule is making a 999 or 112 emergency call.
In a national survey carried out soon after the law came into force, more than a third of drivers admitted they planned to continue using their mobiles at the wheel. Just 17 per cent claimed they would switch off their phone while on the road.
This was despite research showing people were four times more likely to crash while using a mobile.
The Argus went on to the streets and spotted several drivers abusing the law.
Sussex Police warned: "Officers can use their discretion with the enforcement policy.
"If there is a bad crash, it could be brought in as an aggravating factor.
"It is all about road safety and reducing casualties.
"We've all followed a motorist who was swerving or going too slowly and wondered what was wrong.
"When you get past them you realise they have a mobile phone to their ear. You can see they are distracted and driving badly."
Sending text messages while driving is also outlawed and employers may be liable if they fail to forbid employees to use phones on company business.
Sussex Police said the only way to avoid a fine was to use a hands-free car kit, with the phone in a cradle on the dashboard.
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