Just over one-third of organisations with fleet vehicles have a policy banning employees from using hands-free phones at the wheel.
Road safety charity, Brake, says distraction is a factor in many crashes, and the phone call itself is the distraction.
"Drivers who divide their attention are significantly increasing their risk of being involved in a crash," it says.
It's calling for companies with staff who drive for work to ban any cellphone use, in the wake of this year's Fleet Safety Survey .
After last year's survey, numbers increased by 10 percent to 40 percent of organisations around the world banning any cellphone use at the wheel, including hands-free.
Around 200 fleet operators completed this survey; mostly from the UK, but also Australasia, Asia, Africa, North America, and mainland Europe.
Combined they manage a total of more than 190,000 vehicles, and more than 170,000 employees driving for work.
Brake, and the Licence Bureau, conducted the survey, and also found: