Summary

  • Ofcom fined Tismi £437,500 after finding failures in customer checks before number sub-allocation, monitoring afterwards and the handling of misuse reports.
  • The regulator counted about 366,000 sub-allocated numbers exposed to potential misuse over more than two years. Its decision also orders Tismi to produce evidence of how its new controls work.

A provider can answer an alarm and still have no alarm system. In its closed Tismi case, Ofcom acknowledged evidence that the company responded promptly to queries and complaints from outside agencies. The regulator nevertheless found that Tismi lacked a formal, documented way to handle and consistently record reports of number misuse. It was one of three failures behind a £437,500 penalty announced on 21 October.

The numbers begin upstream. Ofcom allocates UK phone numbers to providers, which can pass them to business customers. That hand-off leaves the original holder with duties under General Conditions B1.6, B1.8 and B1.9(c). Ofcom found that, from at least 15 November 2022 to 1 January 2025, Tismi passed numbers on without appropriate due diligence on who would use them. It then had no adequate process to reassess customer risk, monitor for misuse, or identify and address non-compliant behaviour. The missing complaint trail was the third break. A phone number had travelled; the duty to watch it had stayed put.

Ofcom's public announcement puts approximately 366,000 sub-allocated numbers in the pool exposed to potential misuse for over two years. Its investigation identified nuisance and scam calls using some of the numbers. In June 2025, Ofcom directed Tismi to block calls and messages to and from specified mobile numbers, and the company did so. That was an emergency brake on particular numbers, not a substitute for checking customers before allocation and watching them after it.

The price tag has its own audit trail. Ofcom calculated £625,000, then applied a 30% settlement discount for Tismi's admission of liability and the investigative work it saved, reaching £437,500. The regulator also credited cooperation and remedial processes introduced within months of notification. The money goes to HM Treasury. The remaining order is practical: Tismi must show evidence of its due diligence, continuing monitoring and response to misuse reports under its new policies.

Ofcom's good-practice guide had been published in November 2022, at the start of the breach period identified in the decision. This case gives that older guide teeth in a specific allocation chain. A quick answer to an outside complaint mattered, but Ofcom wanted records and routines that would also work before the next complaint arrived.