Ofcom has fined telecoms provider Tismi £437,500 for failing to take appropriate and proportionate steps to stop phone numbers allocated to it being misused, including to carry out scams, the regulator announced on 21 October 2026.
How number allocation works
Ofcom allocates telephone numbers, usually in large blocks, to telecoms providers, which can then pass them on to businesses or individuals. Under Ofcom’s numbering rules and industry guidance, providers must take appropriate steps to make sure the numbers they pass on are not misused, for example to make scam calls or send scam texts. Ofcom expects them to carry out “know your customer” checks on business customers, to keep monitoring for misuse and to respond to reports of it.
What the investigation found
Ofcom found that Tismi did not have any appropriate or proportionate measures in place to prevent misuse of its numbers from at least November 2022 to January 2025. It says the company exposed approximately 366,000 sub-allocated numbers to potential misuse, and a significant number of consumers to harm, for over two years.
Specifically, Ofcom found that Tismi:
- sub-allocated numbers to customers without appropriate due diligence;
- did not monitor whether those numbers were being misused, and lacked the systems and processes to identify and deal with non-compliance;
- had no formal documented process for handling reports of misuse.
During the investigation, in June 2025, Ofcom directed Tismi to block certain numbers so scammers could not keep using them, and Tismi did so. The breaches relate to General Conditions B1.6, B1.8 and B1.9(c).
The penalty
The £437,500 fine includes a 30% discount on what it would otherwise have been, because Tismi admitted liability. The money will be passed to HM Treasury. Tismi must also give Ofcom evidence of its compliance, including details of its due diligence, its ongoing monitoring and how it responds to misuse reports under 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.”
A new investigation
On the same day Ofcom opened an investigation into Xtra Phones UK over concerns that numbers it holds are being misused. It falls under Ofcom’s enforcement programme on phone and text scams, which also covers the investigations into Vonage Business Limited and Voxbone SA that Ofcom opened in September. Ofcom says it will publish a non-confidential version of its Tismi decision at a later date, to protect other ongoing investigations.
For UK businesses that get their phone numbers through a provider, the case shows Ofcom expects identity checks on business customers all the way down the chain, a theme that also runs through the government’s CertifID trust mark rules for verification providers. More telecoms regulation news is in our tech section.
What to watch next: the published Tismi decision and the outcome of the Xtra Phones UK investigation.