Traffic police say using your mobile while waiting for the lights to change is still an offence. You will be fined as much as Bt1,000.

The use of portable phones in vehicles becomes illegal this month. The police promise the grace period will end on May 20. From then, any user of a mobile phone in a vehicle not fitted with hands-free kit will be prosecuted. Fines start at Bt400 and top out at Bt1,000.

A warning for now

In the so-called "transit period", from May 8 to 19, offenders will receive a warning.

Police spokesman Wat-charapol Prasanratchakij says the law takes effect next Thursday. Drivers will be given the transit period to wean themselves off their handhelds.

He warns that the law stipulates that using mobiles while stationary at traffic signals is also an offence. If you simply must take or make a call, pull over and do it, he says.