How to protect yourself from number spoofing scams

Caller and sender IDs can be useful, showing you a number or name when you get a call or text. But four in 10 adults don't know that these systems can be spoofed, leaving them at serious risk of impersonation scams, warns Which?. 

Criminals can use cheap, easily available software to change the number displayed on your phone. By copying the number of a genuine company – such as your bank – they make it much more likely you’ll pick up the phone.

Here, we explain how number spoofing works, the measures being taken to stop it, and how you can protect yourself from scammers.

What is number spoofing? 

There are legitimate reasons for a business to alter its caller ID. For example, it may display a freephone 0800 number so customers can return calls without charge, or use one consistent number if it makes outbound calls from many different lines.

But the same technology is misused by nuisance callers and scammers. It allows them to get around call-blocking devices or trick you into accepting calls you’d rather ignore, such as an overseas call centre showing a UK number.

Public awareness remains low. When we surveyed people in August*, 38% told us they hadn’t heard of number spoofing. This rose to 42% among Generation X (aged 40–59) and Baby Boomers (aged 60–79), leaving millions particularly vulnerable to scammers impersonating banks, energy providers and other trusted organisations. 

Number spoofing can be extremely valuable to a scammer: some 56% of fraud victims who were defrauded after receiving fake phone calls or texts told us it involved number spoofing (survey in April 2024*).

• Find out more: how to get your money back after a scam.

When scammers spoof your number

Scammers don't just impersonate companies – they can spoof your number too.

The first you may know about it is when strangers start calling or messaging you back, angry about contact they believe came from you. This can be intimidating and stressful.

You may feel forced to divert all incoming calls to voicemail with a message explaining the situation, or even change your number. The good news is that scammers usually move on quickly once a number has been exposed.

• Find out more: 'scammers appear to have spoofed my number'.

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What’s being done to stop spoofing?

Ofcom has been working behind the scenes to thwart malicious number spoofing, but progress has stalled.

Notable steps include new industry guidance on blocking calls that spoof UK landlines and the 'do not originate' (DNO) scheme, which protects the phone numbers of some of the most-spoofed organisations such as banks, HMRC and insurers. 

Briefly, the idea is to blocklist numbers that were never intended to make outbound calls. So, if a bank never uses the customer service number printed on the back of its debit cards to make outbound calls, it should enrol that number in the DNO list. Phone networks can then block calls using this caller ID so that they never reach you.

Banks and other businesses can also shield their customers from spoofed text messages, thanks to the SMS SenderID Protection Registry, developed by the Mobile Ecosystem Forum (MEF). This allows brands to register their sender IDs (such as 'HMRC') so that mobile networks can block messages from unverified sources using that name.

These measures can be effective but they aren’t a silver bullet. For starters, neither scheme is compulsory, so many organisations haven’t registered their numbers or sender IDs and can therefore be freely spoofed. Technical constraints also mean that a small number of calls are still connected despite being on the DNO list, and scammers are constantly exploring ways to bypass checks.

Ofcom did have more ambitious plans to crack down on spoofing, through technical standards known as Calling Line Identification (CLI) authentication. However, it has since decided not to go ahead - for now - as the standards would be 'complex, costly and time-consuming to implement' and do not adequately address the issue of scam calls coming from abroad. 

• Find out more: how to spot a text message scam.

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5 ways to protect yourself from number spoofing scams

Although you can’t stop scammers from attempting to spoof numbers, you can take steps to reduce the risk and protect yourself if you’re targeted:

1. Don't trust the name or number on your phone: If you receive a call or message claiming to be from your bank, the police, a government department or any other trusted source, never assume it’s genuine, regardless of the number or name displayed on your phone. 
2. Don’t give out sensitive information on incoming calls: Hang up, wait for five minutes and either call the firm on a trusted number (such as on the back of your debit card or on its official website) or dial 159 to connect to your bank’s fraud team. 
3. Landline call blocking: Ask your provider whether it offers a call screening service such as BT Call Protect and Sky Talk Shield, which allow you to screen unrecognised numbers and block unwanted callers. 
4. Mobile call blocking: Check iPhone and Android settings for call blocking, spam protection and caller ID verification. These services aren't perfect, but they can help. 
5. Call-blocking phones Switch to a call-blocking phone or a TrueCall device that plugs into your existing handset. Both will let calls from your contacts come through, but will ask other callers to leave a message so you can decide whether to pick up. 

*Which? conducted a nationally representative survey with 2,119 members of the UK public, 15-18 August 2025, about their current accounts. Which? also surveyed 1,012 UK victims of fraud who had lost money in the previous two years, 4-15 April 2024. Fieldwork was carried out online by Deltapoll for both surveys.