Ofcom takes world-leading action to crack down on exploitation of mobile networks by criminals

Ofcom has announced new rules that will make the UK a world leader in protecting people from the malicious use of mobile networks.

Ofcom are closing a technical loophole that could pose a risk to mobile users’ privacy and security, by banning the leasing of special types of phone numbers known as ‘Global Titles’.

Criminals can use Global Titles to intercept and divert calls and messages, and get their hands on information held by mobile networks. This could, for example, enable them to intercept security codes sent by banks to a customer via SMS message. In extreme cases they can be exploited by criminals and other harmful actors to track the physical location of individuals anywhere in the world.

Global Titles are used by mobile networks to send and receive signalling messages, helping to make sure a call or SMS gets to the intended recipient. They are used quietly in the background of the billions of calls and texts made worldwide and are never seen by individuals sending or receiving a call or message.

The risk posed by the leasing of Global Titles has been recognised by organisations such as the UK’s National Cyber Security Centre (NCSC) and is acknowledged within the telecoms sector. But industry-led efforts to address these issues have not been effective, Ofcom are stepping in to ban the leasing of Global Titles with immediate effect.

Ofcom’s Group Director for Networks and Communications, Natalie Black, said: “We are taking world-leading action to tackle the threat posed by criminals gaining access to mobile networks. Leased Global Titles are one of the most significant and persistent sources of malicious signalling. Our ban will help prevent them falling into the wrong hands – protecting mobile users and our critical telecoms infrastructure in the process.”

NCSC Chief Technical Officer, Ollie Whitehouse said: “Today’s announcement marks an important step in the support of our mission to make the UK the safest place to live and work online. 

This technique, which is actively used by unregulated commercial companies, poses privacy and security risks to everyday users, and we urge our international partners to follow suit in addressing it. 

As the UK’s National Technical Authority for cyber security, we also congratulate Ofcom on their continued global leadership in this critical area.”

These Global Titles are sometimes leased out by mobile networks – largely to legitimate businesses who use them to offer mobile services. However, they can fall into the wrong hands.

This can lead to the security and privacy of ordinary mobile users being compromised, as their personal data may be directly or indirectly accessed by criminals. And because those who intend to cause harm lease rather than own these numbers, they can hide their identities and work in the shadow of legitimate communications networks.