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The Do Not Originate (DNO) list

23 Chwefror 2022

What is the Do Not Originate (DNO) list?

Consumers may be more likely to trust a call coming from a number associated with a known organisation. In some cases, scammers may deliberately change their number to hide their identity or mimic the number of a legitimate business, e.g. a bank, in order to mislead the consumer. This is known as ‘spoofing’.

Some telephone numbers that are assigned to a business or organisation may never be used by that organisation to make outgoing calls. This may be the case where the number is reserved for inbound calls only e.g. the number on a bank card which is reserved for consumers to report problems to their bank. Any outgoing calls appearing to originate from these numbers will have been spoofed and will not be a genuine call from the organisation.

Ofcom and UK Finance set up the DNO list in 2019 and worked with telecoms companies, devolved administrations, government agencies such as HMRC and other public sector bodies, to record inbound-only telephone numbers that would not be used to call consumers.

The DNO list is shared with telecoms providers (and their intermediaries) to help them identify and block calls from numbers which are not used for outbound calls.. We also share the list with some call blocking and filtering services. These services use technology to block or filter unwanted and nuisance calls on behalf of the consumer, for example via an app or hardware that is installed on a fixed line.

The list has been shown to be an effective tool in combating scam calls using spoofed numbers. For example, HMRC reported a significant reduction in spoof calls as a result of its inbound-only numbers being added to the DNO list. It should be noted, however, that adding a number to the list is not a guarantee that all calls will be blocked. Currently, not all providers apply the DNO list. Further, where providers are using the list, technical telephony constraints may mean that a small number of calls are still connected.

Adding numbers to the list

Ofcom will consider requests to add a number to the DNO list. It should be noted that not all requests can be accommodated and we will prioritise those numbers whose use, when associated with an outgoing call, is likely to lead to the most harm to consumers. Note that we do not add residential numbers to the DNO list.

How to contact Ofcom to add numbers to the list

If you have been assigned a number that you only use for inbound calls and you think it should be added to the DNO list, please contact Ofcom at and follow the steps set out in our guide for submitting numbers to the DNO list (PDF, 201.7 KB).

The same contact should be used if you think a number assigned to you has been blocked in error. Please also contact Ofcom at this email address to discuss access to the list.