uSwitch.com mobiles expert Ernest Doku said: "O2 users affected by this mobile data outage will understandably be concerned and frustrated".
'A statement reads: "The network issue we are now experiencing remains a top priority for us and we are working as quickly as possible to fix the issues. We'd encourage you to use WiFi wherever you can and we are really sorry". In some cases, the 3G network services automatically kicked in.
Fixed line services were not affected.
By April, Ericsson has predicted that there will be six mid-band 5G smartphones, to be followed by two or more mmWave 5G smartphones by July.
"A review will be carried out with Ericsson to understand fully what happened", said O2, which is owned by Spain's Telefonica TEF.MC .
An initial root cause analysis indicates that the main issue was an expired certificate in the software versions installed with these customers.
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France Football has awarded the prestigious prize to the best male player every year since 1956, adding a women's award this year. The suggestion clearly made Hegerberg uncomfortable. "I let them know, quite clearly, what I found wasn't working".
The outage also has serious implications for places that rely upon the O2 network for real-time informational services, as reported by the Independent.
O2 customers impacted by the outage aren't able to access data and the company said they may experience "intermittent issues" when making voice calls as well.
"We're aware that our customers are unable to use data this morning", O2 has said in a statement.
Once the world's biggest supplier of mobile communications gear, Ericsson has lost ground to China's Huawei Technologies [HWT.UL] and Finland's Nokia.
Huawei executive Meng Wanzhou, the daughter of the Chinese company's founder and CEO, was arrested in Canada on Wednesday, at the behest of USA authorities investigating alleged violations of US trade sanctions, according to a source.
Among them are busses, which uses mobile data to transmit timetable information to smart screens on London's network of bus stops, and taxis companies which use mobile apps to get custom and dispatch cars.