By Jonathan Kent
BBC News, Kuala Lumpur
The Malaysian government is to put a stop to the anonymous use of mobiles in response to security fears.
Most of Malaysia's 16 million mobile users using prepaid services
From the end of the year, people using a prepaid service will have to register their details with phone companies.
The decision follows worries about the use of unregistered phones by members of violent militant groups, either to communicate or to trigger explosions.
"The main reason we are doing this is because of security," said Communications minister Lim Keng Yaik.
"It's getting very dangerous. Prepaid cards pose a security threat because nowadays terrorists are using cell phones to detonate bombs."
Rumours by text
Though Malaysia has been almost entirely free of the violence that has plagued other countries in South East Asia, the authorities here are also concerned about a number of instances where wild and unfounded rumours have been spread by text message.
In 2002 villagers in the state of Sabah in Malaysian Borneo fled their homes after SMS messages claimed that head-hunters were roaming the area.
Taking the heads of warriors from rival villages as trophies was common in Sabah before the British colonial authorities put a stop to the practice, but the mere mention of head-hunters still has the power to fuel panic.
In January 2005, less than a month after the December tsunami disaster, thousands of people fled their homes around Semporna, also in Sabah, after text messages warned of another killer wave.
In both instances police believe the rumours were started by thieves who wanted to steal into empty villages to rustle water buffalo or ransack homes.
To stem such rumours the Malaysian government will require new users to show identity cards or passports when they buy a new sim card.
Existing users will have to register when their credit runs out and they have to buy more.
With 14 million out of Malaysia's 16 million mobile users using prepaid services, it promises to be a major task. It will not be helped by the transient status of some phone users.
"A big number of prepaid users are foreign workers, and they do not have fixed addresses," Mr Lim admitted.
Many just live in shacks in the jungle near to factories or on building sites. Nor does the Malaysian government have the best record in enforcing its numerous laws and directives.
However it is unlikely to face opposition from civil liberties groups, who say they have more pressing concerns.
You can hear more on this story on the BBC World Service programme Go Digital