A major mobile network outage has left millions of users in the UK unable to make or receive calls, with Three UK at the centre of the disruption. The outage, which began on Tuesday, June 25, 2025, has also affected a range of virtual mobile operators that rely on Three’s infrastructure. Customers with SIM cards from iD Mobile, SMARTY Mobile, Superdrug Mobile, and Honest Mobile are among those who have found their phones suddenly unusable for traditional voice calls and text messaging.
Three UK has since confirmed the issue and says it is working on a fix, but many customers remain without access to voice services. Some users have even reported being unable to reach emergency services using the 999 number, prompting serious concern. However, there is a workaround that allows users to make and receive calls despite the widespread outage: using VoIP services, or Voice over Internet Protocol.
The problem has left an estimated 10.6 million people, including Three’s pay-monthly and SIM-only customers, unable to connect calls. Compounding the problem, the networks piggybacking on Three’s masts—often used by budget-conscious consumers for their lower prices—have also gone down.
Despite the disruption to voice and text, mobile data remains unaffected. Customers still have access to 4G and 5G services, which means the internet is working even if traditional calls are not. In a statement posted on social media, Three UK addressed the situation directly:
“We’re aware of an issue affecting voice services and are working hard to fix it. Data services are working normally, so calls can be placed via third-party messaging apps. We’re really sorry for any inconvenience caused.”
This has provided a temporary lifeline for users, as it allows continued communication through internet-based alternatives.
Using VoIP apps as a workaround
VoIP services work by using your phone’s internet connection—whether through Wi-Fi or mobile data—to place and receive voice or video calls. Common examples include WhatsApp, Signal, Telegram, Viber, and Facebook Messenger. These apps do not rely on a mobile network’s call infrastructure, so they remain functional as long as the device is connected to the internet.
If you’re affected by the Three UK outage, using a VoIP service is currently your best bet to stay in touch with friends, family, or colleagues. Many people already use WhatsApp and Facebook Messenger for messaging, but both also support voice and video calls. WhatsApp and Viber in particular rely on a linked mobile number, so they can act more like a substitute for your phone’s normal calling function during a network outage.
That said, some apps—like Facebook Messenger and FaceTime—can work without linking your mobile number. In such cases, you may need to ensure your account is properly set up so that people can reach you. For instance, if you use Messenger with only a Facebook profile and haven’t added your mobile number, people trying to call you using that number won’t be able to reach you. It’s worth checking the settings on these apps to confirm that your number is listed, if you want to use them as a substitute phone line.
Emergency call issues spark concern
Worryingly, there have been reports that even emergency services are currently unreachable for some Three users. One video shared on social media shows a call to 999 failing to connect. In response, a customer service representative from Three UK said:
“We appreciate that accessing emergency calls is vital,” and added that the issue had been “passed on to the relevant team to investigate this.”
The company did not exactly state when it would fully resolve the issue. However, its impact is well felt throughout the U.K. At the moment, many users can not make calls, and it can be very frustrating. Also, this issue reveals Three UK’s lack of a robust fallback system for such a critical situation. At the moment, the cause of the issue remains unknown. Whether it stems from Three’s own systems or lies with broader emergency service routing protocols remains to be seen.
Who is affected?
While Three UK is the main provider facing issues, the disruption has also affected customers of mobile virtual network operators (MVNOs) that rely on Three’s infrastructure. These include:
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iD Mobile
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SMARTY Mobile
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Superdrug Mobile
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Honest Mobile
This means the reach of the outage is significantly broader than Three’s direct customer base. People who may not even realise they are connected via Three’s masts have found their voice services unexpectedly cut off.
The issue also reveals the fragile nature of how UK telecoms are structured. Many smaller carriers lease infrastructure from larger operators. This means a single point of failure can knock out services across multiple brands.
What to do next
If you’re affected by the outage, apps that rely on internet access may still work for communication.
These include WhatsApp, Signal, Telegram, Viber, Messenger, iMessage, and FaceTime, all of which use data, not voice.
You can call or message others using these apps if you have Wi-Fi or a working data connection.
Let your contacts know they should reach you through these apps instead of making regular phone calls.
Posting a message on social media can help people know the best way to get in touch. This is especially useful if someone has been trying to call without knowing you’re not getting any calls. Some people may not use these apps often, especially those more comfortable with traditional calls and text messages. Even so, this is currently the only practical solution for staying connected while the outage continues.
Waiting for a fix
Three has said it is “working hard” to fix the problem, but has not provided a detailed timeline or explanation. Without further updates, customers are left to rely on alternative communication methods indefinitely. It remains unclear whether compensation will be offered to affected users. Though the severity and length of the outage might pressure the provider to consider such measures.
In the meantime, users are advised to monitor official channels from Three UK. This includes its website and social media profiles for the latest updates. The statement issued by the company is brief and does not say much. However, the guidance to switch to third-party apps has at least helped many find an alternative during the disruption. For now, mobile users on Three and its partner networks will need to rely on internet-based calling methods.
