The fault also affected Japanese users of the SoftBank network, as well as carriers who use O2's network like Sky Mobile, GiffGaff and Tesco Mobile.
O2 has said that services are slowly being restored to customers tonight.
O2 will be facing scrutiny from its customers in the coming months, as the company is pressured to implement more countermeasures in future.
Ericsson said in a press release that most services had been restored.
"Voice calls are working OK". They're now working hard to resolve the issue so we would imagine it won't be too long before its back up.
SoftBank Group Corp's mobile phone services were disrupted in some parts of Japan on Thursday, but it was unclear whether its problems were related to those of O2.
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Her family was surprised and anxious when she didn't contact them on her birthday or get in touch over on the days that followed. CCTV image from December 1 shows the last known sighting of Grace Millane whose 22nd birthday was the next day.
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This morning he worked with the physiotherapist on the pitch, running and touching the ball. "[Friday] will be the decision". The news comes at a time when Holding was emerging as a serious candidate to break into Gareth Southgate's England squad.
"One of our 3rd party suppliers has identified a software issue in their system".
Angry customers have since slammed the network, calling it an "embarrassing and insulting gesture" with some saying the credit should be donated to charity instead.
Following network disturbances in a number of Ericsson's (NASDAQ:ERIC) customer networks, Ericsson has taken immediate action to minimize impact and support the restoration of services. The faulty software that has caused these issues is being decommissioned. However, neither Ericsson or O2 have given any indication of when the problems might be fixed. "We'd encourage our customers to use Wifi wherever they can, and we apologise for the inconvenience caused". An Ericsson spokesperson confirmed that it was aware of the issue, and was working on a fix.
O2 customers can check when the latest update on the network here.
The network said: "We're really sorry for the issues you experienced on Sky Mobile yesterday".
For customers wishing to complain, regulator Ofcom said they should follow O2's formal complaints procedure, which is available on the network's website. O2 also provides a range of services that suffered as a result, from Oyster card readers to security systems that rely on GSM (Global System for Mobile communications).