Millions of suspicious calls from scammers abroad will be blocked as UK telecoms rules become stricter, the communications regulator has said.

Ofcom said in future phone companies will have to stop calls from abroad which imitate UK landline numbers, a practice known as “spoofing”.

The requirement, which comes into effect in January 2025, is designed to protect people who are more likely to trust a call because it appears as a UK number on their handset.

Ofcom also called for firms to come up with “innovative solutions” to tackle fraudsters who imitate UK mobile numbers.

“In 2024, just under half of UK landline users (48%) said they’d received a suspicious call in the last three months,” Ofcom said.

“A common tactic used by criminals to defraud victims is to imitate or “spoof” phone numbers from a trusted person, organisation, or government department, so their calls are more likely to be answered,” it added.

The new blocking measures would have a “significant impact” on protecting the public from scam calls, Ofcom said.

A recent study of around 2,000 people suggested some were receiving on average two fraudulent calls a day. The study also showed that over-75s were particularly vulnerable to scammers.

“Scam calls can result in significant financial and emotional harm to victims. They can also lead to a reduction in trust in telephone calls,” said Ofcom’s Lindsey Fussell.

Ofcom’s tightening of the rules comes after a period of consultation.

The watchdog said that as part of a voluntary exercise during that time, BT was already preventing “up to one million calls per day”.

Ofcom advises people not to trust the caller ID display on their phone when trying to avoid scams. It also instructs people not the give out personal information in response to an incoming call.

If you think you’ve been a victim of Caller ID spoofing, it advises calling Action Fraud on 0300 123 2040 or visit www.actionfraud.police.uk.