Cellular service disruptions along the Gulf Coast have made communication even more difficult for the million people who lost their landlines to Hurricane Katrina. Mobiles are unusable in many of the flooded areas. And some New Orleans residents who got out of the city have reported problems using their cell phones, even in regions that Katrina left unscathed. Why have cell phones been so affected by the flood?
Because the water damaged both land-line and cellular equipment. If water has destroyed the electronics at the bases of the cell-phone towers nearest to where you are, you won't be able to use your phone at all. (Even the equipment that stays dry may face a loss of power—rooftop cell-phone stations tend not to have their own generators.) If you do make it out of the flooded areas, your cell phone may be hampered by its disaster-ridden area code. Calls to cell phones get routed through local land lines, so phones programmed with New Orleans area codes (504 and 985) will have problems receiving calls wherever they are.
When someone dials a cell-phone number from a land line, the call travels to the cell phone's area code via a landline network. If you tried to call your friend on his Verizon Wireless phone with a 504 number, your call would automatically go to a local Bell South switch in the New Orleans area. Then Bell South would transfer the call over to Verizon's local Mobile Telephone Switching Office, or local network hub. The MTSO would then communicate with other Verizon MTSOs to figure out where your friend happened to be, and transfer the call over to the nearest cell-phone station or tower.
So even if you and your friend were sitting in the same room in California, your call would bounce across the country, and might get hung up on a drowned switch in New Orleans. (Both land-line and cell-phone switches have been affected by the flood.) On the other hand, your friend could probably call you. If he placed a wireless call from California, it would travel first to the local cell station, and then to the local MTSO, and then directly to your phone via local California landlines. According to the cellular service providers, those with 504 and 985 area codes who have made it out of New Orleans can change their numbers or add a line with a new area code, at least until the switching problems are cleared up.
Why can't the cell-phone companies just reroute the entire 504 and 985 area codes? In general, the information about your phone's area code is programmed on the phone itself, and changing it would require both a live connection with the company, and a certain sequence of button presses from the customer—code swaps would have to be made on a phone-by-phone basis. Companies are also reluctant to make any wholesale changes that might affect 504 and 985 cell phones that are still working—some of which belong to rescue workers and law-enforcement officials.
Explainer thanks Ritch Blasi of Cingular Wireless and Patrick Kimball of Verizon Wireless.