Call traceback

Trialling faster processes to identify the sources of scam calls 

‘Call traceback’ is the process by which information about a phone call (metadata) can be gathered from the different communications providers that were involved in its transmission.

Ofcom is trialling new traceback processes through a proof of concept. Below we set out information for communications providers about this trial, the process we will follow when making requests for traceback information and what providers need to do if they receive a request.

Background

Ofcom is exploring the benefits of improving traceback processes to combat scam calls, following commitments from communications providers under the 2025 Telecommunications Fraud Sector Charter and the publication in January 2026 of the UK Government’s updated Fraud Strategy.

Primarily, we are exploring how improving traceback processes could strengthen Ofcom’s supervision and enforcement capabilities.

Since 2014, NICC has maintained guidelines (ND1437) for tracing calls. These guidelines allow for Ofcom and the Information Commission (ICO) to request traceback information from communications providers. Earlier this year, NICC reviewed this standard and proposed a range of alternative approaches for call tracing in the UK. 

In the light of this report and following our own review of current call traceback processes, we consider that an improved process could help support Ofcom’s work in combatting scam calls.

Aims of the trial

We are trialling new traceback processes. Our proof of concept aims to:

• Determine whether new processes and a consistent operational framework can make traceback requests more successful.
• Test these internal and external processes in response to feedback to improve results.
• Evaluate the utility of the information that can be gathered through traceback for Ofcom’s supervision and enforcement activities in relation to scam calls.
• Help us to better understand the impact and resource burden of running a continuous traceback function on Ofcom and communications providers.

At this stage, we expect the trial to last for several months. We will initially review progress against our aims early in 2027. Following the trial, Ofcom will determine whether new processes have the potential to become business as usual, in the context of our wider priorities.

Process Ofcom will follow

Ofcom will initiate traceback requests using intelligence we receive about suspected scam calls. 

We will normally make a first request to the terminating communications provider asking for information about the call, including which provider the call was received from. In parallel, we may also contact the range holder or suballocatee of the telephone number present in the Calling Line Identification (CLI) to check whether the call came from their customer. If it did not, then we would continue to request information from each upstream provider until we: a) reach the originating provider; b) identify the provider that brought the call into the UK, or; c) a provider fails to respond.

Once a decision is made to conduct a traceback, we will do so systematically (step by step) through the chain of providers (even where we may have received intelligence that could indicate the provider that originated the call).

For the purposes of this trial, we intend to begin by issuing formal information requests under section 135 of the Communications Act 2003. It is important respondents provide clear, complete and accurate responses to all the questions by the deadline given in the request. Where this does not happen, we may open an investigation into a provider’s failure to comply. In turn, this may result in a significant financial penalty.

Due to the nature of call data, which providers may not typically preserve for extended periods of time, these requests will have a short deadline of 1-2 working days. We will also issue them in final form, rather than in draft. Whilst we consider that this is necessary and proportionate for our purposes, we are committed to working with communications providers throughout the POC trial to understand any potential barriers to responding to traceback requests and providing the necessary data quickly.

As the trial progresses, we may seek to determine whether issuing informal requests for information could help ensure traceback operates smoothly and reduce burdens on industry, while generating the information we require. We would contact providers to establish arrangements for such requests.

Initial format of traceback requests 

The table below sets out the core data provided to, and requested from, each provider as part of a traceback request, in the format we intend to use at the beginning of the trial. We are sharing it to help industry understand the specific call information that we may request from you during the proof of concept. However, it is subject to change as the proof of concept develops and our processes evolve to help improve results and outcomes.