I wanted to comment as a Londoner on the WSJ report from London that Monty Solomon posted
The writers say that "the communications problems indicate that, at least in Britain, cellphone-system operators may not have learned many lessons from the Sept. 11, 2001, terrorist attacks in the U.S."
On the contrary, what they have clearly learned from is the March 2004 attacks on Madrid, where 191 people were killed by a series of bombs in trains set off by cellphones. It's clear that, while there was undoubtedly huge traffic on the networks (fixed and mobile) in the hours after the very similar attacks on London, the network operators followed a well known, though fortunately little used, procedure of restricting network access.
Two reasons: partly to give the emergency services priority. Though they of course have their own two-way radio networks for use within individual services (police, fire/rescue, ambulance) they also use the regular mobile phone networks because these give them access to other services, such as hospitals, transport officials, utilities, local and national government, including social services. When there is a major incident access to non-essential users can be blocked by the networks: this is a procedure that has existed at least since the 1960s - though it was a lot more complex to operate in step-by-step Strowger switches than it is now.
But secondly, as I heard the sirens on Thursday morning and saw the police cars and ambulances hurtling past to Liverpool Street station (close to my office) and the other sites, I was only too well aware of what happened in Madrid 16 months ago.
Those bombs on the underground could not have been set off by mobile phones as there is currently no coverage in the tunnels - the experience of Madrid was a genuine cause for concern when Transport for London announced plans a couple of months ago to let networks install base stations. They were, it now seems, set off by electronic timers -- all three bombs, at Edgware Road station, between Liverpool Street and Aldgate stations, and between Kings Cross and Russell Square stations, went off within 50 seconds of one another. Which presumably means someone actually decided that 08.51 was precisely the most effective time to kill people, as commuters would then be on the last few minutes of their journeys to work for an 09.00 start.
However, it was clearly possible that there might be a second wave of explosions on the above-ground trains that carry more millions of people into central London each day, including me to work and my daughters to school, and that cellphones might be used to set those off. So I was not surprised that it was impossible to make outgoing calls from mobile phones in the affected areas (calls to the 999 emergency number, the equivalent to and the predecessor of the North American 911, would not have been blocked). And incoming calls were automatically diverted to voicemail -- avoiding any chance of calls getting through to phones that were wired into bombs. We still don't know how the fourth bomb, on the bus, was set off -- the police are still, literally, putting the pieces together.
Alan Burkitt-Gray Editor, Global Telecoms Business magazine, London