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In fact, this very problem is why there is a US government program that lets certain emergency personnel/offices have priority over normal telephone traffic.

This is also why we don't normally see phone numbers in the 710 area code.

See: http://gets.ncs.gov/program_info.html for an overview.

(Wow, I feel like I'm back on comp.dcom.telecom)

And why should they?

Precisely. Public safety authorities in the US know they would cause themselves much more harm than good by shutting down the cell network, even if they could. They themselves use it (many have Wireless Priority Service to get priority access to the next available voice channel on the local tower). People calling 911 need it. EMTs and ambulances often use patient monitoring gear that sends telemetry data over the cellular network. You're screwing up a lot more things than you're fixing if you want to shut down the network.

It's a different story in some other countries where bombing is much more frequent than in the US (and where the government also often owns or has direct control over the telecoms)... network shutdown is actively used there in some cases. But anytime you hear something about the cops or authorities shutting down cell service in the US, don't believe it.

Well, way back when it was a parameter called ACCLOC, which determined the priority of traffic. Cellular networks has "Wireless Priority" http://wps.ncs.gov/carriers.html to ensure that emergency services rise above the noise.

Untrue -- Government officials and emergency personnel have a special code they can use to dial numbers on their cell phone, giving them priority access to the cell towers.

http://wps.ncs.gov/use.html

Dial *272 and then the number you want to call. If your phone is flagged as allowed to use WPS, then your call will be accepted and given priority over all other calls. I believe there are differing levels of access, so a local volunteer fireman might have a lower priority than say Secretary of State Clinton.

There are a variety of strategies that allow cellular networks to function in these situations, and to ensure that certain phones can almost always use the network. http://wps.ncs.gov/

WPS and GETS did not work from my cellular phone during this time. This was quite a severe outage, and caused 'No Service' for a very wide area locally as well. I did not determine if it was due to the tower being without power though, most sites have 8-12 hours of standby power at most.

WPS and GETS did not work from my cellular phone during this time. This was quite a severe outage, and caused 'No Service' for a very wide area locally as well. I did not determine if it was due to the tower being without power though, most sites have 8-12 hours of standby power at most.

As far as managing the situation in a disaster, there is a solution already in place for the bandwidth issues - WPS and GETS. These simply cause certain phones or calls to have priority over other calls. The protocols that manage phone networks always leave space for a few calls available when they begin to provide a congestion tone on a normal call. GETS and WPS bypass these phone company imposed restrictions. This allows for about a 90% call completion rate for priority calls.

  "When the going gets tough, GETS keeps you going."

As far as managing the situation in a disaster, there is a solution already in place for the bandwidth issues - WPS and GETS. These simply cause certain phones or calls to have priority over other calls. The protocols that manage phone networks always leave space for a few calls available when they begin to provide a congestion tone on a normal call. GETS and WPS bypass these phone company imposed restrictions. This allows for about a 90% call completion rate for priority calls.

  "When the going gets tough, GETS keeps you going."

You mean something like: http://gets.ncs.gov/

(This is PIN-based instead of hardware based, but one can reasonably argue that that's probably better.)

I'm a former Ericsson employee - my telecom knowledge is a bit out-of-date, but the basics never go away :-)

Plain SMS'es are be sent on control channels (SDCCH or SACCH), and for every one control channel, there are many more voice channels. In some configurations, SDCCH and SACCH reside in the same time slot as the control channel for setting up calls - but not in others. It's a configuration issue really. Yes, in a badly configured network, you can jam voice calls with SMS'es. But with a good configuration (and monitoring and blah blah), it's not a problem.

Some SMS'es have a higher priority than others - for example emergency broadcasts, and can therefore reach the recipient while "normal" attempts to send an SMS get an error message ("network busy - please try later"). Read the article about SMS over SS7 - quite interesting! Read about the 9/11 tragedy's effect on cell phones.

The US Government SHARES service reports that radio HF, VHF and UHF radio are the only means of communication available. "SHARES was used in numerous cases [August 29] to facilitate communication coordination for both federal and military agencies, and also rescue efforts for stranded civilian personnel," John Peterson said.

Peterson said SHARES, which is part of the National Communication System, will continue to be a major communication facility for federal government agencies and military units responding to the Katrina emergency, and "SHARES stations should be prepared for extended operations." He encouraged any and all reports from affected areas.

SHARES is continuing operation 24/7 on government communication frequencies of 14.3965 MHz days and 7.632 MHz nights throughout the disaster response.

I already in another post mentioned the NCS GETS system:

http://gets.ncs.gov/

(the 710 area code system used for disasters).

As for cell phones there is something called "Overload Class". Emergency personnel have theirs set to 15, which means their calls get priority.

http://gets.ncs.gov/

This is what the infamous 710 area code is for.

I don't know how well it actually works or if it is being used for this disaster.

Anyone know if it was used on 9/11?

Packet based technology is INTRINSICALLY less reliable than circuit switched.

Running it over their own network will help somewhat, I admit, but the fundamental shortcomings of the technology remain.

Plus the temptation to push the existing infrastructre beyond its maximum reasonable capacity is too hard to resist in many cases.

With circuit switched, you just CAN'T have more circuits available than there is infratructure to support it. With packet switched, you kinda sorta can, but get degradation in service which worsens as load increases. If the September 11 attacks occurred with packet based phone networks being the norm, the impact on phone service would have been much much worse. You'd get a call "through", but you'd hear silence 95% of the time, and gibberish the other 5%. With circuit switched, either an error message or a good connection. And with the Government Emergency Telecommunications Service at least critical NS/EP (National Security/Emergency Preparedness) calls would get through.

Homeland Security depends on circuit switched public telephone networks.

With Sprint moving away from circuit switching and to a packet switched network for public conventional voice services, VoIP likely won't have the disadvantage of less reliability compared to the public telephone network.

Call attempts that fail with errors due to network issues and congestions, silence and distortion due to dropped packets, dropped calls, etc will likely become more common.

Phones are critical. They are counted on to help save lives. Packet switching just isn't up to the task. The gov't should intervene and say the public telephone network must stay circuit switched. It even risks Homeland Security issues. The Government Emergency Telephone System (home of the legendary and formerly secret 710 area code) http://gets.ncs.gov/ might be needed to save many lives, and be unable to due to the unreliability of packet based networks,

I'll confirm that (although, to satisfy the other response, let's say "infrastructure" instead of "network"). I work in telco network disaster recovery. As an organization, we've got just about every form of voice comm you've ever heard of. To talk to the world away from our recovery location, the final fallback is a high-frequency radio on the SHARES network.http://www.ncs.gov/n3/shares/shares.htm
If the fibers are cut, the cell towers are down, and the satellite's over the horizon, that radio is still going to work.

The Clinton Administration has also developed and provided full or pilot funding for the following key initiatives designed to protect the Federal Government's computer systems: ....

• Piloting Public Key Infrastructure (PKI) Models.
  The Clinton Administration is funding seven PKI pilot programs in FY 2001 at different Federal agencies. ($7 million)

I don't feel like pouring through all the trolls to see if anyone posted this linke earlier, but here's the proper link for the US Government Emergency Telecommunications Service (GETS)

http://gets.ncs.gov/