Editor's note: Amy Gahran writes about mobile tech for CNN.com. She is a San Francisco Bay Area writer and media consultant whose blog, Contentious.com, explores how people communicate in the online age.
(CNN) -- September is National Preparedness Month -- do you know where your cell phone is, and how to use it during an emergency?
According to The New York Times, U.S. wireless networks proved fairly resilient when Hurricane Irene recently swept the eastern seaboard. Many people who lost power or landlines were still able to communicate via cell phones using voice calls, text or multimedia messaging, e-mail, and social media.
Of course, in this case wireless network operators had days to prepare for the storm. As CNET reported, they were able to get generators and backup equipment in place to keep their cell towers functioning. This would not be possible for sudden kinds of emergencies, such as tornadoes or earthquakes.
So in those emergencies, expect that you might not have cell service immediately -- and be prepared with information, supplies, and skills to get you through that crucial time.
Soon after an emergency strikes (within hours or days), carriers usually bring in extra cell phone towers on wheels -- and generators or solar cells -- to compensate for damaged towers or to supplement coverage in areas where evacuees or emergency responders are located. So after an emergency cell networks are among the first pieces of infrastructure to come back online -- often before power, landlines, and drinking-water systems.
The Federal Emergency Management Administration's Get Tech Ready page offers some handy tips for getting your phone ready to use during an emergency. Here are some of the basics:
"Keep your contacts updated across all of your channels, including phone, e-mail and social media. This will make it easy to reach out to the right people quickly to get information and supply updates. Consider creating a group list serve of your top contacts."
"Learn how to send updates via text and Internet from your mobile phone to your contacts and social channels in case voice communications are not available. Text messages and the Internet often have the ability to work in the event of a phone service disruption."
"Keep extra batteries for your phone in a safe place or purchase a solar-powered or hand crank charger. These chargers are good emergency tools to keep your laptop and other small electronics working in the event of a power outage."
This part may be a little more challenging than you'd expect.
Power is a key challenge. While smartphones offer the most mobile-communication options, they're also notorious energy hogs with batteries that tend to last less than a day with average use. So if, like 35% of Americans, you own a smartphone, it's a good idea to know how to trim your power consumption so you can extend your battery life in an emergency.
Lifehacker published a great guide to saving your smartphone's battery. It might be worth printing that out and storing it in your emergency kit -- but also read it over and try out the measures it recommends now, when you're not in a rush, to figure out what works best for you and your phone.
Low cell signals can drain your battery quickly because your phone can expend considerable energy searching for towers. So if you see that you have little or no cell signal, it might be a good idea to turn your phone off most of the time and just check in occasionally to see if better signal has returned. If the signal is low, turn off your 3G or 4G data connection if possible most of the time and stick to low-bandwidth uses like text messaging.
Although FEMA recommends keeping your contacts updated across all your channels, that can be a challenge. While contact syncing works fairly well on some phones, on others it's confusing and unreliable. (I've definitely found that to be a challenge with my Android phone.) So don't underestimate the low-tech fallback: paper.
Personally, I maintain a text file that lists all important phone numbers, e-mail addresses, URLs, Twitter IDs, and shortcodes that I'll want to have in an emergency. I print that out every time I update it, and store the latest copy in my emergency kit.
Make sure your local office for emergency management is on that list -- as well as the local offices for places where your loved ones live or work. Find out which of these offices offer text-messaging alerts, or have numbers where you can send text messages in an emergency.
Also, learn to do as much as you can with text messaging. For instance, you can update Twitter via text message, and interact with many other online services (such as your bank, or some insurance companies -- so make sure all relevant account numbers are in your emergency kit, too). Text messaging is a clunky interactive interface, so practice this skill in advance. Don't try to learn it during an emergency.
It may also be a good to have a simple second cell phone as an emergency. You don't need to pay a monthly bill on it, just get some prepaid minutes or text messages. Very simple phones tend to hold a charge much longer than smartphones or even many feature phones.
The Motorola Motofone F3 is the phone I keep on hand for emergencies. It holds a standby charge for months, and can operate for weeks on a single charge. I keep my important phone numbers and shortcodes programmed in it.
The catch is, prepaid minutes expire -- so if you go this route, mark your calendar to use your minutes before they expire, and recharge the SIM card with the carrier as needed.
A hand-crank charger is a must-have part of your emergency kit. A solar charger may also help, but hand-crank chargers can be used day or night and tend to charge phones faster. Many emergency radios include a hand-crank charger and mini or micro USB ports. So keep a couple of extra cables in your emergency kit to charge your phone.
If you use Dropbox (a cloud-based file storage service) or Evernote (a free service for taking, storing, and sharing notes), it may be a good idea to post your important documents and contact info in a private folder there, install the associated apps on your smartphone, and practice using it on the go.
Both services also offer the ability to share folders with selected individuals -- so in advance you might want to share an "emergency info" folder to some people you trust who live in other parts of the country. They could use these services to send you the text of news stories and Web pages, maps, e-mails, and more to help you get through the emergency -- and you can access this in one place, whenever you have time or connectivity (whether on your phone, or maybe a computer in a shelter).
You can also use your mobile phone to assist emergency responders locally or elsewhere by gathering important information to coordinate relief efforts. This can range from knowing how to tweet usefully, to adding information to crowdsourced crisis maps, to supplying photos or videos of affected areas.
But the most important points are to keep a cell phone and charger in your emergency kit, know how to keep it charged, program in the numbers and info you'll need, keep that information up to date, know how to use it to send text messages, and (if prepaid) make sure the minutes aren't expired.
More emergency preparedness tips and tools can be found here: Ready.gov.
The opinions expressed in this post are solely those of Amy Gahran.