UK communications regulator Ofcom partnered with UK Finance to build the Do Not Originate (DNO) number database in 2019. Maintained jointly with telecom operators, HMRC and other government bodies, it targets caller ID spoofing fraud. The list contains institutional numbers designed only to receive inbound calls and never to make outbound calls, such as bank service hotlines.
This database is shared with telecom operators, intermediary service providers and third-party call filtering vendors. If a call’s calling number appears on the DNO list, the call is definitively spoofed fraud, and operators may identify and block it at network level. After HMRC added its inbound-only numbers to the list, scam calls impersonating the authority dropped sharply, proving the effectiveness of the mechanism.
Organisations may submit forms to apply for adding their inbound-only numbers to the DNO list. Ofcom prioritises numbers whose spoofing would cause substantial consumer harm. Private residential numbers are not accepted. However, DNO is not an absolute safeguard. Due to technical constraints, not all service providers have deployed the list, so a small volume of scam calls may still get through. Issues such as false positive blocking can be reported to Ofcom via the designated email address.
