Telecoms provider fined £437,500 for failing to prevent misuse of its phone numbers by scammers

Ofcom has today fined telecoms provider, Tismi, for failing to take appropriate and proportionate steps to ensure allocated numbers were not misused, including to perpetrate scams.

Ofcom allocates telephone numbers, usually in large blocks, to telecommunication providers. They can then transfer the numbers to individuals or other businesses.

In line with Ofcom’s numbering rules to protect consumers  and industry guidance, phone companies must take appropriate steps to ensure that numbers we have allocated to them are not misused by businesses or individuals they have transferred them to. Misuse of numbers could, for example, include using them to facilitate scam calls and texts.

In order for phone companies to tackle misuse of numbers, we expect them, among other things, to carry out ‘know your customer’ due diligence checks on their business customers to prevent scammers from accessing valid numbers in the first place. Additionally, they should keep the level of risk posed by a business customer under review by monitoring for potential number misuse and respond appropriately to any incidents of misuse reported to them.

What our investigation found

We have found that Tismi did not have any appropriate or proportionate measures in place to prevent misuse of numbers allocated to them at least between November 2022 and January 2025. The company exposed approximately 366,000 sub-allocated numbers to potential misuse, and therefore a significant number of consumers to harm, for over two years. In doing so, Tismi also failed to meet the expectations set out in our Good Practice Guide.

Specifically, our investigation uncovered that Tismi;

• sub-allocated numbers to its customers without carrying out appropriate due diligence to ensure the effective and efficient use of those numbers and prevent them from being misused, including for perpetrating scams;
• failed to monitor whether numbers it had sub-allocated were being misused, and did not have the appropriate systems and processes in place to identify and address non-compliance; and
• did not have a formal documented process in place to handle reports of misuse.[1]

During the course of our investigation, we issued a direction to Tismi to block certain numbers in June 2025, to prevent them from being used further by scammers. Tismi put this block in place.

Financial penalty

As a result of Tismi’s serious failings, Ofcom has fined the company £437,500[2], which will be passed onto HM Treasury.

As part of our decision, we are also requiring Tismi to complete further actions to evidence its compliance. This includes providing details of its due diligence process and on-going monitoring, and its response to reports of incidents of misuse in accordance with its new policies and processes.

George Lusty, Ofcom’s Director of Enforcement, said: “There’s no excuse for communications providers failing to put in the proper checks and balances to prevent numbers being misused. Today we’re sending a clear message to industry that any company that puts customers at the mercy of scammers will face the consequences.”

Opening a new investigation

Ofcom has also today opened a new investigation into Xtra Phones UK, relating to concerns that telephone numbers held by this company are being misused.

This investigation falls under our enforcement programme looking specifically at phone and text scams. The aim of this programme is to protect customers by supporting best practice in the use of phone numbers and to ensure providers are following Ofcom’s rules.

On your side

Ofcom has recently launched a new online Consumer Hub - www.ofcom.org.uk/onyourside - offering a wealth of tips, including around how to protect yourself against scams, alongside money-saving advice, help with common service problems and routes to complain.

Notes to editors

1. General Conditions B1.6, B1. 8 and B1.9(c)
2. The penalty includes a 30% discount on what it otherwise would have been given Tismi’s admission of liability.
3. To protect the integrity of other on-going investigations, a non-confidential version of the Confirmation Decision will not be published until a later date.