Telecom service providers have been told to block 50 numbers used by call centre gangs to trick their victims and have been given two months to develop a system to counter caller-ID spoofing via Voice over Internet Protocol (VoIP).
The measures are part of efforts by law enforcement officials to tackle phone scammers, the National Broadcasting and Telecommunications Commission (NBTC) said.
The move was unveiled on Friday following a meeting between the NBTC, the Royal Thai Police (RTP), the Anti-Money Laundering Office (Amlo), commercial banks and six telecom operators.
NBTC secretary-general Takorn Tantasith said they agreed on a slew of measures to prevent the public from falling prey to transnational call centre scam gangs using VoIP services.
The gangs make calls from VoIP services such as the popular messaging app Line and use software to hide the original ID while displaying fake numbers, he said.
Most of the numbers used belonged to police stations, court houses and post offices, he said, adding they totalled about 50.
The fraudsters pose as police officers, state officials or bank employees and make false accusations about drugs or debts to scare the victims into handing over their personal information or valuables.
Six telecom operators have been told to block the numbers used to make calls via VoIP to victims since December.
For a long-term solution, the telecom service providers are required to develop a system to keep logs of all calls made from VoIP platforms to identify the caller's real identity over the next two months.
With this, all calls made via VoIP platforms must show the real calling numbers to receivers under the local telecom operators system, Mr Takorn said.
"Incoming calls via the VoIP network to all destinations in the country can't be changed to fake numbers like the gangs want. This will help receivers verify the calls," he said.
"The system is expected to be completely upgraded by March. That will directly obstruct those gangs which are using fake numbers."
The six telecom operators are TOT, CAT Telecom, Advanced Info Service (AIS), Total Access Communication (DTAC), True Move, and Triple T Broadband (3BB).
Mr Takorn said a task force set up to prevent call centre scams was set up last month and has so far reported 50 VoIP numbers have been used to rip off victims.
The Royal Thai Police (RTP) have detected 11 victims since December, saying they were defrauded out of a combined 8 million baht.
Authorities returned 1.6 million baht to the victims yesterday that had been retrieved from the scammers.
Mr Takorn gave an example of how the scam typically worked.
Masquerading as a police officer or bank clerk, the caller would inform the intended victim they were suspected of having committed a financial crime, for example money laundering.
The would then request information to verify the victims' claims of innocence and have them perform a so-called "checking procedure" at an ATM.
They were told this was to avoid having their account frozen but it would often result in the victim unwittingly transferring money to an account held by the gang.
Pol Maj Gen Surachet Hakphan, deputy chief of the Police Tourism Bureau, said the swindlers frequently devise new tactics, with the latest involving the use of fake arrest warrants.
He said police have issued 275 warrants for people involved in such scams and have arrested 162.
In a related development, Pol Gen Thanitsak Thirasawat, a senior adviser to the RTP, said police are investigating commercial banks over an identity theft case involving 24-year-old Nicha Kiartthanapaiboon.
Ms Nicha has sought help from the Crime Suppression Division (CSD) to track down people who used her ID card to open nine accounts with seven banks, which were used to handle the proceeds of a call centre scam.
She has been charged in connection with the scam but insists she is innocent and her ID card was stolen last October.
"I sympathise with her but her arrest was made in line with procedures. Police will investigate and give her justice," Pol Gen Thanitsak said.
Police will look into the role of commercial banks to determine if they were negligent in failing to follow the proper authentication process, he added.
Pirapat Ingpongpan, a representative of the Anti-Money Laundering Office, said that commercial banks can face a maximum fine of 1 million baht for flouting the rules.