Cellular network operator O2 on Friday said its data networks had been restored after millions of smartphones across the UK and Japan were taken offline yesterday (via BBC).

A statement on its website said the 4G network was finally working again, after having been affected from about 05:30 GMT on Thursday.

o2 ericsson
Earlier, mobile network equipment supplier Ericsson said that an expired certificate was the reason behind the outage, which also created problems in several other countries. Ericsson UK boss Marielle Lindgren said the "faulty software" that had caused the issues was being decommissioned.

Both O2 and Ericsson issued a joint apology to millions of customers hit by the disruption. "I want to let our customers know how sorry I am for the impact our network data issue has had on them, and reassure them that our teams, together with Ericsson, are doing everything we can," said O2 boss Mark Evans. "We fully appreciate it's been a poor experience and we are really sorry."

O2 is owned by Spain's Telefonica and has the UK's second-largest mobile network after British Telecom subsidiary EE.

The company said voice calls were not affected by the problem, but some O2 customers said they could not make calls or send texts, despite having cellular reception.

The outage also had knock-on effects for other services that use the O2 network, such as Transport for London's electronic timetable service at bus stops, which stopped working for most of Thursday.

Top Rated Comments

fullfast Avatar
91 months ago
Vodafone is the Verizon of the UK. I’ve tested all the networks and for me it was the best by far. Glad O2 is good for you
30 million total impacted by it and all because some dope forgot to renew a certificate so it expired.....that is just pi$$ poor management

Luckily for me I am on both Vodafone and o2 so minimal impact but it does just show how reliant we are now on being able to access internet services.......rewind 15 years....you were lucky if you could receive texts let alone look at what some dog or cat is doing on insta :)
Score: 4 Votes (Like | Disagree)
BMcCoy Avatar
91 months ago
As frustrating as yesterday’s outage was, I still think we do quite well in the U.K. for our cellular deals, whether calls or data. We pay about a quarter of what it costs in the US.
Score: 4 Votes (Like | Disagree)
jimthing Avatar
91 months ago
I moved from O2 to EE when I got a Series 4 on launch. Very happy. My wife and kids are on O2 still, and I didn't hear from them all day yesterday. Who do I send the thank you letter to?
Here's the address:

(FAO) 'Men escaping constant annoying trivial family calls' dept
Santa Claus
iCloud
Earth
Space
Universe
Score: 3 Votes (Like | Disagree)
NoFace1006 Avatar
91 months ago
Vodafone is much better.
You're joking aren't you?! Although I should say that everyone has different experiences and it depends where you live, etc. Had several family members on Vodafone over the years and it's always been terrible for data, particularly data reception more so than the speed. In the end everyone has moved over to other networks, I've been with 3 for 18 months after switching from O2's network, couldn't be happier. Went to the top of Scotland to visit family, a no reception area for most networks in places, I was the only family member with signal and data access.
Score: 3 Votes (Like | Disagree)
coumerelli Avatar
91 months ago
They apologize by you still get billed for the time it was out I bet...
Yeah. All 0.17£/€/¥. lol
Score: 2 Votes (Like | Disagree)
roar08 Avatar
91 months ago
It'll be interesting to find out of this tantalizing Mac rumor turns out to be true.
Score: 2 Votes (Like | Disagree)

Popular Stories

iOS 26

15 New Things Your iPhone Can Do in iOS 26.2

Friday December 5, 2025 9:40 am PST by
Apple is about to release iOS 26.2, the second major point update for iPhones since iOS 26 was rolled out in September, and there are at least 15 notable changes and improvements worth checking out. We've rounded them up below. Apple is expected to roll out iOS 26.2 to compatible devices sometime between December 8 and December 16. When the update drops, you can check Apple's servers for the ...
Intel Inside iPhone Feature

Apple's Return to Intel Rumored to Extend to iPhone

Friday December 5, 2025 10:08 am PST by
Intel is expected to begin supplying some Mac and iPad chips in a few years, and the latest rumor claims the partnership might extend to the iPhone. In a research note with investment firm GF Securities this week, obtained by MacRumors, analyst Jeff Pu said he and his colleagues "now expect" Intel to reach a supply deal with Apple for at least some non-pro iPhone chips starting in 2028....
ive and altman

Jony Ive's OpenAI Device Barred From Using 'io' Name

Friday December 5, 2025 6:22 am PST by
A U.S. appeals court has upheld a temporary restraining order that prevents OpenAI and Jony Ive's new hardware venture from using the name "io" for products similar to those planned by AI audio startup iyO, Bloomberg Law reports. iyO sued OpenAI earlier this year after the latter announced its partnership with Ive's new firm, arguing that OpenAI's planned "io" branding was too close to its...
iPhone 17 Pro Cosmic Orange

10 Reasons to Wait for Next Year's iPhone 18 Pro

Monday December 1, 2025 2:40 am PST by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models at the same time, which is why we often get rumored features months ahead of launch. The iPhone 18 series is no different, and we already have a good idea of what to expect for the iPhone 18 Pro and iPhone 18 Pro Max. One thing worth...
Photos App Icon Liquid Glass

John Gruber Shares Scathing Commentary About Apple's Departing Software Design Chief

Thursday December 4, 2025 9:30 am PST by
In a statement shared with Bloomberg on Wednesday, Apple confirmed that its software design chief Alan Dye will be leaving. Apple said Dye will be succeeded by Stephen Lemay, who has been a software designer at the company since 1999. Meta CEO Mark Zuckerberg announced that Dye will lead a new creative studio within the company's AR/VR division Reality Labs. On his blog Daring Fireball,...
maxresdefault

iPhone Fold: Launch, Pricing, and What to Expect From Apple's Foldable

Monday December 1, 2025 3:00 am PST by
Apple is expected to launch a new foldable iPhone next year, based on multiple rumors and credible sources. The long-awaited device has been rumored for years now, but signs increasingly suggest that 2026 could indeed be the year that Apple releases its first foldable device. Subscribe to the MacRumors YouTube channel for more videos. Below, we've collated an updated set of key details that ...
Johny Srouji

Apple Chip Chief Johny Srouji Could Be Next to Go as Exodus Continues

Sunday December 7, 2025 10:41 am PST by
Apple's senior vice president of hardware technologies Johny Srouji could be the next leading executive to leave the company amid an alarming exodus of leading employees, Bloomberg's Mark Gurman reports. Srouji apparently recently told CEO Tim Cook that he is "seriously considering leaving" in the near future. He intends to join another company if he departs. Srouji leads Apple's chip design ...
Apple John Ternus 2019

Will John Ternus Really Be Apple's Next CEO?

Friday December 5, 2025 9:01 am PST by
There is uncertainty about Apple's head of hardware engineering John Ternus succeeding Tim Cook as CEO, The Information reports. Some former Apple executives apparently hope that a new "dark-horse" candidate will emerge. Ternus is considered to be the most likely candidate to succeed Cook as CEO. The report notes that he is more likely to become CEO than software head chief Craig Federighi, ...
ios 18 to ios 26 upgrade

Apple Pushes iPhone Users Still on iOS 18 to Upgrade to iOS 26

Tuesday December 2, 2025 11:09 am PST by
Apple is encouraging iPhone users who are still running iOS 18 to upgrade to iOS 26 by making the iOS 26 software upgrade option more prominent. Since iOS 26 launched in September, it has been displayed as an optional upgrade at the bottom of the Software Update interface in the Settings app. iOS 18 has been the default operating system option, and users running iOS 18 have seen iOS 18...
iOS 26

Apple Seeds iOS 26.2 and iPadOS 26.2 Release Candidates to Developers and Public Beta Testers

Wednesday December 3, 2025 10:33 am PST by
Apple today seeded the release candidate versions of upcoming iOS 26.2 and iPadOS 26.2 updates to developers and public beta testers, with the software coming two weeks after Apple seeded the third betas. The release candidates represent the final versions of iOS 26.2 and iPadOS 26.2 that will be provided to the public if no further bugs are found during this final week of testing....