July 7 2005 began as a normal day at T-Mobile. Then, workers at the mobile telephone operator’s UK service management centre, workers noticed that some call traffic routes were starting to get very busy. Before long, alarms were flashing red on operators’ screens.

“There were no faults as such, but our processors were being pushed extremely hard,” says Martin Pigott, head of service operations at T-Mobile UK. Managers switched on the news to discover the cause of the unusual activity – a huge surge in mobile phone usage in the immediate aftermath of the London bombings.