ONE THING THAT WE’VE LEARNED SINCE 9/11, and again during the Great Blackout, is that the cellphone network isn’t just a luxury for rich guys and soccer moms anymore: it’s a vital part of emergency infrastructure.

Unfortunately, we’ve also learned that it isn’t up to the job:

Less than two years after the cellular network faltered following the Sept. 11, 2001 terrorist attacks, the cellular system — which the wireless industry promotes as a safety net during emergencies — choked again.

The system broke down as a flood of nervous callers overloaded the network for some carriers; there wasn’t enough capacity to handle the excess calls. Complicating matters, many cellular sites, which depend on electricity, had inadequate backup power.

Cell-phone carriers say the electrical outage was an event they couldn’t possibly foresee.

I don’t think that’s much of an excuse, and I think that cell-phone technology is mature enough that it’s fair to start expecting the kind of robust reliability that we’ve seen from landline services. This is too important to ignore.

No backup power? Puhleez. Well, okay “inadequate” backup power, as the story illustrates. Still, the cell network is vitally important, and yet it still has the reliability standards of a rich man’s toy, which it hasn’t been for a long time.

Of course, it’s not just cellphones. Backup power for traffic lights — at least at key intersections — would help deal with the traffic problems often associated with disasters, and even an hour or so of that would help clear the worst of the traffic.

There will be more about this in my TechCentralStation column this week.

UPDATE: Reader Ari Ozick emails:

Your note on Cell Phones and emergencies was right on target. It may surprise you to know that even in Israel, we have the same problems with our cell phone networks. When a terrorist attack happens, you can’t get a line on the 3 major networks for a good 15 minutes to a half hour. The fourth network, which is much smaller, currently can handle the overload, because it’s system doesn’t carry as much capacity as the other three regularly do.

The cell phone saturation in Israel is much more then that of the United States, and yet almost everyone I know keeps a telecard (good for a certain amounts of credit on a public phone, sort of like carrying a few quarters in your pocket) in their wallets, so that if they are out during an attack or an emergency and the cells are down, they can still call loved ones and reassure them.

Hmm. It seems that we should be sure not to let payphones die out, since they’re more reliable than cellphones. It also seems that we should educate people not to immediately call loved ones to “reassure” them when other folks may need something more concrete than reassurance.

ANOTHER UPDATE: Reader Steve Sandvik emails:

I work in power generation, and I think that although this is a big black eye for the power industry (especially transmission), the difference in response and apparent level of concern between the cell phone industry and the power industry is very enlightening. They’re selling themselves as part of your disaster response toolbox, but they don’t want to pay for it.

That’s right. I’ve noticed that power workers have a sense of mission that cellphone people definitely lack.

MORE: A reader emails that Verizon wireless was up throughout the blackout, unlike other companies. Bravo!

STILL MORE: Solar-powered traffic lights are apparently feasible, at least in sunny San Antonio. Read this, too.

MORE STILL: Steven Den Beste, who knows a lot more about cellphones than I do, has a post on this subject. He says it’s a difficult problem — though I think regulation could ensure enough excess capacity to address the situation. But to the extent I’m wrong it’s yet another reason to keep those payphones around, I guess.