Number spoofing

Ofcom /

What is Number spoofing?

These days, most telephone handsets display the phone number of the person calling you; this is a feature known as ‘Caller ID' or 'Calling Line Identity' (CLI).
This feature is quite handy; a lot of people use it for call screening and decide which calls they want to answer.
Unfortunately, there is a growing trend of criminals and nuisance callers deliberately changing their Caller ID to hide their true identity, this is a practice known as 'Number Spoofing'.

Why does number spoofing exist?

Number spoofing is not always bad and there are many genuine use cases for number spoofing; some people use Apps like the TTNC Softphone App and want to present their DDI or main office number, rather than their mobile number. Another legitimate use case is when someone wants to present an 0800 freephone number, so that people can call them back for free. Both of these use cases are genuine and legitimate.
However, some people are using number spoofing for all sorts of wrong reasons, such as trying to hide their true identity or to imitate the phone number of a real company that they have nothing to do with.

How do criminals use number spoofing?

Despite strict rules being in place in the UK and other countries, criminals often find flaws and bugs in systems that allow them to manipulate the CLI to be displayed to the receiver of a call.
Quite often, the criminals will have their own telecoms equipment which manipulates the CLI. They will then connect this equipment to a telecoms provider that hasn't got adequate checks in place. This enables them to present whatever number they want to when making calls.
In nearly all cases, criminals will use number spoofing to gain your trust and to steal sensitive or valuable information. For example, they can present your bank's phone number when calling you to get your account information from you.

What should you do?

Firstly, you should never give someone your personal details and information in response to an incoming phone call, or rely upon the Caller ID as the only means of identification.
If a caller asks for your banking details or other sensitive information, do not provide it. You should end these types of calls, wait 5 minutes and then call a phone number from your statement, phonebook or from an official website for the company, bank or government department to check if the call was genuine.

Tell Action Fraud

Action Fraud is the UK's national reporting centre for fraud and internet crime. If you have been targeted by a scam, or know someone who has then call Action Fraud on 0300 123 2040 or visit
Please note: If debit cards, online banking or cheques are involved in the scam you should first contact your bank or credit card company.

Tell Trading Standards

The Trading Standards service is responsible for protecting consumers against rogue traders and traders acting unfairly.
You don't contact Trading Standards directly; you should call the Citizens Advice Consumer Service on 03454 04 05 06. They can then pass on your details to Trading Standards.

Tell others

Spread the word and warn everyone you know, including friends, family and neighbours, the more people that know about a scam, the less harm it can do to people.

Useful information

Ofcom has published some useful information on their website about number spoofing and nuisance calls