If your business takes you to or through a few airports on a regular basis you already know if the Wi-Fi is free (and the location of the power outlets and best coffee).
But it's often less than straightforward to jump online if you start or end your trip in an unfamiliar airport.
Many airports proudly promote their free Wi-Fi on concourse signs, on their websites and whenever someone in the airport opens a browser.
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"As airlines consolidate and airports compete for traffic and air service, every little amenity helps to lure flyers, and free Wi-Fi is a great perk to keep consumers happy while they wait for the flights," said Airfarewatchdog President George Hobica.
But, citing economic factors and long-running contracts, many airports still charge for Wi-Fi or offer just a few minutes of free access. Some airports, including O'Hare and Midway in Chicago, allow travelers to visit some tourism and shopping websites for free, but if you want to check email or conduct business, it will cost you. Still others are moving to a hybrid plan offering limited Wi-Fi for free but more robust service for a fee.
"A typical airline passenger carries two Internet-enabled devices such as a laptop and smartphone, or a smartphone and tablet," said Henry Harteveldt, a travel industry analyst and strategist with Hudson Crossing. And because many of these devices are bandwidth hogs, "we're seeing some airports charge extra for high-bandwidth activities such as audio and video downloads."
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You can poke around an airport's website for the status of the Wi-Fi offered, but there are a few other ways to determine if an airport offers free or fee-based Wi-Fi.
Jaunted (part of the Condé Nast Traveler Network) has an airport Wi-Fi map that draws Wi-Fi status information from the on-the-ground experiences of its writers and tips from travelers who use the map and send reports on where they've successfully accessed complimentary airport Wi-Fi.
"The main challenge right now is noting what networks are truly free and unlimited (examples: Hong Kong, JFK's Terminal 5) and which are ad-supported, limited-time connections, as the latter is becoming more common, but not less confusing," said Managing Editor Cynthia Drescher of Jaunted.com.
The team at Airfarewatchdog just published its own downloadable airport Wi-Fi chart offering a snapshot of the Wi-Fi offered at many popular U.S. and international airports. But because Wi-Fi contracts at many airports are in flux, even a chart released two week ago will need to be updated.
Detroit Metropolitan Wayne County Airport, for example, is listed as "pricing unavailable," but travelers currently get 30 free minutes of free Wi-Fi per device. In September the airport will switch providers (from Boingo to AWG) and begin offering free, faster Wi-Fi. (An advertisement will be shown every 45 minutes and paid higher-speed Wi-Fi will also be available.)
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The Airfarewatchdog chart also doesn't include the fact that in Houston, both George Bush Intercontinental Airport and William P. Hobby Airport offer 45 minutes of complimentary Wi-Fi to passengers. According to airport spokesperson Darian Ward, the goal is to begin rolling out completely free Wi-Fi in some terminals by the end of the year.
If you're at an airport with a fee for Wi-Fi and you are unwilling to enter your credit card information, some travelers have had luck getting passwords for the Wi-Fi signal in airline lounges and cafes by using a free mobile phone app or search engine to look on sites such as Faceboook, Foursquare or Twitter for passwords being shared by other travelers. (But you didn't hear that here.)
—By CNBC Contributor Harriet Baskas. She is the author of seven books, including "Hidden Treasures: What Museums Can't or Won't Show You," and the Stuck at the Airport blog. Follow her on Twitter at @hbaskas.