MEF Director of Programmes Nicholas Rossman discusses the news that UK regulator Ofcom has introduced new rules surrounding Global Titles for UK telephone numbers, that could have major implications for mobile network security.
In a significant development for the UK’s mobile network security landscape, the communications regulator Ofcom implemented new rules on April 22, 2025. At the heart of this decision is a ban on the leasing of Global Titles (GTs) associated with UK telephone numbers.
This move, strongly supported by the National Cyber Security Centre (NCSC), aims to address a persistent technical vulnerability within mobile network signaling infrastructure that has been increasingly exploited by malicious actors.
To understand the implications of this decision, it’s crucial to grasp what Global Titles are and why their leasing has become a security concern. Global Titles are essentially network addresses derived from telephone numbers. They play a fundamental role in routing signaling messages across mobile networks, enabling various services we rely on daily.
However, the practice of leasing these GTs to third parties has inadvertently created a security loophole. By gaining access to these leased GTs, malicious actors can tap into the global signaling network. This access opens the door to a range of harmful activities, including the potential interception of sensitive communications, the ability to illicitly track the location of individuals, and even the disruption of network operations.
For the industry as a whole, this development serves as a clear signal. Proactive engagement and the development of robust solutions are crucial to prevent further regulatory interventions on a global scale.”
While the misuse of Global Titles isn’t a new issue, previous industry-led efforts to combat the associated fraud have, unfortunately, fallen short.
Initiatives such as the GSMA Global Titles Code of Conduct and the MEF 2016 Code of Conduct on Global Titles, while well-intentioned, have not proven sufficient to deter determined fraudsters. This lack of effectiveness ultimately necessitated regulatory intervention.
Ofcom’s new rules reflect this reality, with an immediate cessation of new GT leasing arrangements and a defined transition period for existing agreements to be phased out.
It’s important to acknowledge that Global Titles serve essential functions within mobile communications and have been utilized for legitimate business purposes.
Mobile Virtual Network Operators (MVNOs) and various service providers, for instance, have historically relied on leased GTs for their operations. The new ban, therefore, presents tangible operational challenges for these legitimate players.
They will now need to navigate the complexities of migrating to alternative solutions to ensure the continued delivery of their services.
In conclusion, Ofcom’s recent action represents a decisive step towards bolstering the security of the UK’s telecommunications infrastructure. By addressing the vulnerabilities associated with Global Title leasing, the regulator aims to create a more resilient and secure mobile environment for users.
However, the long-term success of this measure will likely depend on the broader international landscape.
For the industry as a whole, this development serves as a clear signal. Proactive engagement and the development of robust solutions are crucial to prevent further regulatory interventions on a global scale.
Without such efforts, more regulators worldwide may feel compelled to take similar action to protect their national telecommunications infrastructure and their citizens.
