The London 2012 Olympic Games begin on Friday, bringing with it thousands of extra users vying for bandwidth on the city's mobile networks.
The recent O2 outage underlined how a loss of connectivity can hit hard — and it can't afford to happen during the Olympics. So have the big UK mobile operators and content powerhouses like the BBC learnt to play nicely together to ensure services stay online?
One group in particular is getting to grips with making sure all is plain sailing. The Mobile Experience Group (MEG) brings together service providers and content companies (the BBC, YouTube and Twitter), and puts them in a room with Games organisers, Ofcom and London authorities to work on making sure the Olympics data surge doesn't disrupt normal usage.
"MEG's all about making sure there is a sensible dialogue between the demand side and the supply side; we've done that for the last couple of years," the group's chair Stuart Newstead said.
"[This means] when the BBC is putting together what it's going to do on iPlayer, it'll have a good understanding of what the networks will be able to do, and vice versa. And when the networks are being built, they have a good sense of what the demand is likely to be," he noted.
One of the problems with planning for the expected increase in mobile traffic during the Games is that the demand will come from a range of sources, according to Newstead.
For example, people inside the Olympic Park will want to get specific information on competitors in the events they are attending. Others, outside London, are more likely to want to see results, watch live-streamed events or use their phone as a companion to watching the competition on TV.
As a result, there is no one metric that can be used for capacity planning, Newstead said. Instead, he said it makes more sense to think about the demand on mobile as equivalent to "four Cup Finals a day, or three royal weddings, for three-and-a-half weeks".
So, with all the infrastructure planning that has gone into the Games, will the big four UK mobile networks be able to cope with demand? Here's a look at what have they done to batten down the hatches.
One of the key problems for the operators is the sheer amount of traffic expected to pass across the networks, something O2 believes will be like the surge of commuters the London Underground sees twice a day.
"The mobile industry is expecting to cater for 80 million mobile phone users in 100 different event locations," Derek McManus, chief operating officer of O2, has said.
"But it's not just about the volume of people. We know that the nature of sporting and entertainment events means that we see huge spikes in traffic at key moments, such as when a goal is scored, or a number-one song is played. It's the equivalent of rush hour on the Underground."
In preparation, O2 has spent more than £50m on increasing capacity and building temporary sites across the UK ahead of the event. Despite this, the company is planning to use a Wi-Fi offload to help deal with the massive demand on data services.
The joint venture between T-Mobile and Orange began beefing up capacity for London 2012 before the two companies merged, it said.
"Everything Everywhere [is] investing millions of pounds to ensure a good experience for both British and international visitors to the Olympics," it said.
"Our network specialists have looked to previous global and national events, and analysed sites around the UK where we expect additional demand over the course of the summer — including tourist attractions, transport hubs and sporting venues — and upgraded hundreds of key sites to cope with additional demand."
The company did not want to reveal exactly how much extra capacity it has put in place, or how much money it has spent doing so. However, it did give details of how much the Joint Operators Olympic Group (JOOG) — which includes all major UK mobile providers — has put in place.
In total, JOOG has deployed 30 mobile base stations, including some in 14 indoor locations. It has built a further 17 temporary sites at venues outside the Olympic Park to increase capacity further.
Three told ZDNet it had been working alongside other members of JOOG to build additional and dedicated capacity at the Olympic venues in London and around the country.
In addition, the network said the works had coincided with its on-going network improvement plan already underway nationwide.
"We've upgraded sites at around 500 different locations and have also upgraded most of our sites nationally to the very latest and quickest 3G technology (HSPA+). Later this summer, we will move to Dual-Carrier HSDPA equipment, potentially doubling the speed customers can currently get," Three said.
As well as investing in upgrading the mobile sites, Three has also installed ethernet backhaul across its entire network, providing more capacity and higher speeds in transferring data from the mobile sites to its core network.
As a member of JOOG, Vodafone too has been getting ready for the massive spike in data and calling traffic. It told ZDNet it spent more than £1.5m a day in 2012 on work.
"The Olympics are different... Everything is on a scale that's different from anything that has been done before" — Stuart Newstead
Much of the investment was made in the first half of the year "in preparation for a busy summer", Vodafone said. This includes ensuring extra coverage in public spaces such as Hyde Park in London, where crowds of Olympics visitors are expected to gather.
Vodafone would not say exactly what traffic load it expects to see during the Games. On a normal day, the network sees upwards of 45TB of data usage, 90 million phone calls and around 90 million text messages, and it is planning for "a significant increase" on that level of demand, it said.
MEG has used the lessons it learned from large events such as Wembley concerts, Cup Final games, the royal wedding and New Year's Eve. However, he noted that, as with an important football match, it's the spikes of traffic that are the hardest to model.
"Each operator has done its own planning for demand, and then there's been a lot of infrastructure sharing when it comes to actually building it; building the most capacity, given the laws of physics and the cost limitations," Newstead said.
"The Olympics are different. It has required a different level of co-operation to other events. Everything is on a scale that's different from anything that has been done before."