A handful of companies have built the networks that operate in the majority of Wi-Fi-equipped airports in the U.S. and Canada. Most of these hotspot builders only sell service on a day-pass basis, leaving monthly plans to resellers who aggregate airport service with other hotspot offerings.

Resellers typically offer session rates below what you would pay as a walk-up pay-as-you-go customer, but they almost all have unlimited monthly service plans as well that include access to other hotspots in their networks.

To keep costs low, check out the prices from resellers who serve the airports your frequent, as well as day pass rates, and estimate the number of times you would use the service per month (at both airports and other hotspots) to decide if a monthly subscription is worth it.

Pay as you go

If you aren't interested in a recurring service plan, you will typically pay $4.95 to $9.95 for Wi-Fi access using a session pass at an airport. A "session" is usually defined as a single calendar day or 24 hours starting from the time of activation.

To pay for a session, select the network from your laptop or handheld and launch a Web browser. Attempt to visit any page, such as Google or JiWire.com, and your browser will be redirected to a payment/login page. (Virtually all operators protect credit card transactions by using SSL encryption, keeping your personal information safe. If you dont see "https" at the start of the Web address in the Location field and a lock icon or other encryption signals in your browser window, dont proceed.)

A small number of operators offer system-wide day passes: buy a DayPass from T-Mobile at the San Francisco International Airport (SFO), for instance, and you can use any T-Mobile HotSpot for the next 24 hours anywhere in the U.S. Since many airports (and airline lounges) use T-Mobile, a little planning can let you connect everywhere along your route with one day pass.

Monthly Plans

The monthly plan with the widest airport coverage right now is that offered by Boingo Wireless, which requires you to use special software thats available for Windows, PocketPC, and Mac OS X 10.3 or later. Boingo charges $21.95 for unlimited access to all of its domestic locations, including airports, which encompass those operated by Wayport, Concourse, and ICOA, for a total of 85 in the U.S. and five in Canada at this writing. A Boingo subscription includes the second month free and can be canceled and resumed at any time without additional charge.

Cingular Wireless Wi-Fi service, recently announced, includes selected airports operated by Wayport, Concourse, and SBC for a total of 21 in the U.S. and Canada, including large airports such as Seattle and Minneapolis-St. Paul. Cingulars unlimited usage plans require a subscription to its GPRS/EDGE data plan. The three cheapest data plans, from $19.99 to $39.99 per month, include Wi-Fi for an extra $39.99 per month. For the $49.99 per month data plan, Wi-Fi adds $29.99 per month. And for the unlimited data plan at $79.99, Wi-Fi is just $19.99 per month extra. Cingular also requires special software to use its network.

T-Mobile has a large pool of available hotspots, but only the 12 airport-wide locations it operates are covered in its unlimited usage monthly plan. T-Mobile's unlimited plan does include dozens of airport club lounges, but not the expense of being a member. T-Mobile has roaming relationships with other airport hotspot operators, but charges negotiated roaming fees per session for those networks. With a one-year commitment, T-Mobile HotSpot charges $19.95 per month for T-Mobile voice subscribers and $29.99 for others, or $39.99 for a month-to-month plan. Roaming fees vary by location and are added to your T-Mobile bill.

For the general public, no other networks or resellers include enough airports as part of an unlimited monthly rate to be worth signing up with just for their airport coverage. GoRemote, iPass, FiberLink, and other corporate remote access resellers also bundle dial-up, wired, and hotspot access into company-wide service plans that cover most North American airports at a discounted daily rate.