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The carrier's 4G problems have hit the networks 25 million customers, as well as those using networks that rely on its infrastructure, like GiffGaff and Tesco Mobile.
But it is also causing problems in places that rely on O2's network coverage for other important services.
Transport for London's live timetables, for instance – which allow people to see accurately when a bus is about to turn up at any given stop – appears to have broken and is showing that no buses are arriving. That appears to rely on O2's data connections to work, and since buses are unable to connect to the central service the entire system is broken.
TfL is yet to comment on the outage but its site shows that no London buses are arriving at bus stops. The buses themselves are of course running as normal.
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"We’re sorry that customers are unable to use our Countdown screens at bus stops for live travel information," a TfL spokesperson said. "This is a result of a nationwide O2 data outage. We are working with our service provider to resolve this as soon as possible."
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Numerous people tweeted at O2's official account – which has been attempting to offer updates on the problems throughout the morning – to express their frustration over the fact they were unable to get onto the internet.
Some users even asked for compensation for the outage period. Regulator Ofcom says that it is unlikely that carriers will have to offer refunds for the problem period, but that such a payout is possible if it lasts for a long time or the network wants to make amends.
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