Phone companies will automatically block almost all internet calls coming from abroad, under plans to combat foreign fraud, Ofcom has said.
All international calls found to be falsely using a UK number will be barred, the regulator said.
Criminals have been using internet-based calling technology to make it look like a phone call or text is coming from a real telephone number – often one based in the country they are targeting.
Almost 45 million consumers were targeted by phone scams between June and September this year.
"We've been working with telecoms companies to implement technical solutions, including blocking at source, suspicious international calls that are masked by a UK number," said Lindsey Fussell, Ofcom's networks and communications group director.
"We expect these measures to be introduced as a priority, and at pace, to ensure customers are better protected."
Fussell said that tackling the phone scams issue was a "complex problem" that requires a coordinated effort from the police, government, other regulators and industry.
Internet-based calling technology, also known as Voice Over Internet Protcol (VoIP), is used by millions of consumers globally to make phone calls free or cheaply every year.
Popular services that use this technology include WhatsApp, Skype, Zoom and Microsoft Teams.
Businesses also use the VoIP technology for internal corporate phone networks.
Whenever a corporate phone network makes a call, a VoIP provider hands over the call from the internet to the phone networks.
Gabriel Cirlig of US cyber-security firm Human, said criminal gangs are using this method to trick consumers into parting with their money.
"Because of this lower barrier of entry, it is very easy for scammers to build their own systems to spoof mobile numbers - the cybercriminals are essentially pretending to be legitimate corporate telephone networks in order to have access to legitimate telco infrastructure."
Experts agree that the only way to completely fix the problem is to implement new telephone identification protocols that enable phone networks to authenticate that all calls and text messages actually come a real telephone number.
At present, landline customers can request to have nuisance calls blocked by registering on the Telephone Preference Service.
The free opt out service allows you to record your preference on the official register and not receive unsolicited sales or marketing calls.
Companies (including charities) who choose not to screen but subsequently call a number on the register can be fined up to £6,500 for each registered number they call.
If you receive a call from an unsolicited number, Action Fraud’s advice is to not share any personal or financial information, hang up and contact the organisation yourself using a trusted source – such as the telephone number on the back of your bank card.
