I am an executive, but I do not use a BlackBerry. Oh, I know such people: I see you in airports, blowsy but serious in rumpled suits, bent frowning over the little screens of your preferred smartphone, thumbs flying over its little keys. I know you are loyal to the devices, developed and designed by Canada’s Research in Motion. You like the reliability of BlackBerry’s email service and your chief technology officer, who bought the machine for you, feels sure your communications are secure.

But last week’s BlackBerry outage, undercuts RIM’s remaining competitive advantage. Reliable communications were the thing that RIM did best: smart phones from other manufacturers possess more appealing features and run more software. I too, was a loyal BlackBerry customer for many years. But I switched to Apple’s iPhone two years ago.

What happened last week was caused by RIM’s dependence on a centralised private network to push encrypted emails from the email systems of companies to individual BlackBerrys. A router in RIM’s operations centre in Slough in the UK – which relays emails in Europe, India, Latin America and Africa – crashed. RIM did not understand what was wrong until unsent messages accumulated in a global cascade. It took RIM three days to recover. And while Mike Lazaridis, co-chief executive of RIM, apologised for the outage, promising $100 in free apps, the crash has prompted wider questions about the future of the BlackBerry.