Although police had discretion over enforcement, flouting the ban was a ticketable offence, Mr Register said.
More than 634 tickets for breaching the ban have been issued in the Wellington police district, which includes Wairarapa, in the past year.
National road policing manager Superintendent Carey Griffiths said the campaign was timed to remind drivers about the risk of distractions.
"We are now several years down the track. We don't see any excuses for people still failing to comply with this legislation."
Drivers flouting the ban face an $80 fine and 20 demerit points.
While the law allows the use of hands-free phones, they must be completely voice activated or securely mounted and operated infrequently.
Drivers were not allowed to create, send, or read text messages under any circumstances, Mr Griffiths said.
Police have handed out more than 28,000 tickets nationwide since the legislation came into effect - 11,342 in the past year.
AA spokesman Mike Noon said the ban had made a difference to driver behaviour.
"We think initially the public were pretty good, they got on board. But what we're hearing now is that people slipped back into their old ways."
Mr Noon said the AA supported the police blitz as a wake-up call for drivers but he said penalties needed to be reviewed.
Mr Griffiths said other common driver distractions included changing a CD, unrestrained pets, arguing children, things rolling around in the car, eating, and applying make-up.
"Driving a car is not something to be taken casually. Everyone should approach driving with respect. After all, for most people it is the most dangerous activity they will ever undertake."
Police drivers remain exempt from the ban if they use mobile phones in the execution of their duties.
A coroner's finding last year found a Northland police officer ran over and killed a 16-year-old pedestrian 23 seconds after receiving a text from a female acquaintance in 2009. A phone records search could not confirm whether he had opened the message.
Tragedies since the ban include the case of pedestrian Phyllis Penman, 93, knocked down and killed in Hawke's Bay by Curtis Lawson, 21, as he read a text in March 2010.