Today is Red Nose Day , the main day of fundraising for UK charity Comic Relief. But it's a bit more complicated to carry off today than it was when the charity started in 1985.

"This year's event represents the highest density of digital donations the UK will have ever seen," explains Martin Gill, head of new media at Comic Relief . "The new focus on digital transaction-handling is being driven by heightened UK broadband customer numbers.

Pipex is behind the huge infrastructure needed to power Red Nose day. The company started preparing for the project in late 2005 after the last Red Nose Day. The first task if faced was to building a platform ready for Sport Relief 2006 - this would prepare the infrastructure for this year's event.

Pipex is working for Comic Relief alongside technical partners including APC, Cisco, Empirix, Oracle, Sun Microsystems and WorldPay.

Today, the platform will carry both VoIP (Voice over IP) traffic to calls centres as well as the huge amount of data traffic that will pass through the company's website today. The effect will go on for weeks as people hand in their cash.

The infrastructure isn't just for transactions either; it's also built to handle high numbers of visitors to Comic Relief's website which Pipex provides.

The Sport Relief systems passed £0.5 million every fifteen minutes during the live programme on BBC One last July.

The effect of huge peaks in data is called "flash crowd traffic," named after the flash mobbing phenomenon.

"We don't like to project volumes or cash amounts before the night," says Gill, "but for planning purposes, we have been testing the platform up to 1,000 transactions per second to allow for some head room."

Pipex reckons its platform will handle over 700,000 transactions during this evening. It cites a transaction time of less than two seconds, even at times of peak demand.

The company maintains Comic Relief's infrastructure in two of its data centres, located in London and Manchester. There are 20 servers at the Harbour Exchange site and nine more at the secondary site in Manchester.

There is also off-site backup while one site can take over from the other in case of any problem.

Since its 1985 launch Comic Relief has raised nearly £450 million. The last Red Nose Day, in 2005, raised £65 million for projects in the UK and Africa.