Some 18,000 feet above Washington state -- Shortly after takeoff from a Seattle airstrip, about the time flight attendants typically start wheeling out drink carts, another intoxicating experience begins on this Boeing 737: high-speed, wireless Internet access.

The experience of instant messaging, emailing and Web surfing from a laptop in the sky is like discovering those technologies for the first time ("honey -- u there? we just flew over mt. rainier!!").

It's also scary. If there's any glamour left in what used to be called jet-setting, it's the blissful isolation of air travel. When else can people truthfully tell colleagues and friends that they're out of reach? Yet, the solitude of the sky is coming to an end.

The plane I was on was a demonstration flight for Boeing's Connexion Internet service, available on 72 commercial aircraft operated by Singapore Airlines, Lufthansa and others. That number will jump to about 100 by the end of the year.

For now, Internet service is mainly on long-haul international flights. Domestic carriers have had far more important things -- like staying out of bankruptcy court -- to worry about. But they, too, are coming around.

United Airlines, in partnership with Verizon Communications, hopes to begin offering high-speed Internet access on some of its planes by the end of next year, eventually expanding the offering to its entire fleet.

For the Blackberry generation, Internet withdrawal is too much to bear, especially during overseas business travel. "To be out of touch for 10 or 12 hours is a pretty traumatic experience," says Tim Vinopal, director of engineering at Connexion by Boeing.

So far, the biggest controversy surrounding the new in-flight communication technologies is the use of personal cellphones in cabins. The Federal Aviation Administration and the Federal Communications Commission are considering lifting the current ban. But the fear that passengers jabbering for hours on their phones in close quarters could make life miserable for others, and even worsen air rage, is making some Capitol Hill lawmakers and the Association of Flight Attendants oppose ending the ban.

Meanwhile, an online survey of 50,000 mobile-phone users by International Data Corp. this year found that only 11 percent favor the use of cellphones on flights, though 64 percent approved of quieter activities, such as text messaging and emailing.

The debate over cellphones is missing the point, though. Voice calls are already happening in the sky through Internet services like Connexion. And they are, relatively speaking, dirt cheap. On my Boeing demonstration flight, I used a popular voice over Internet program for PCs called Skype to call friends and colleagues, wearing a headset plugged into my laptop.

Calls between Skype users on computers are free of charge, but it's easy to make calls to old-fashion telephones through a service called SkypeOut, which costs just two cents a minute from any location, including the air, to countries like the U.S., the U.K. and Japan. Connexion's Internet service costs $10 for an hour, $17 for two hours or $30 for an entire flight.

The total bill, then, for someone who talked for two hours on a Skype call in the sky would come to about $19.40. In contrast, a two-hour domestic call through a traditional in-flight phone service, such as Verizon's Airfone, costs more than $480, or less if you are a Verizon Wireless customer.

The quality of my Skype calls was mostly excellent, but they did highlight a problem. While people on the other end of the line were easy to hear, I had trouble hearing my own voice above the din of the airplane. A number of my callers later said I seemed to be shouting at them. Imagine the horrific effect of a couple dozen people screaming into their headsets at once.

If voice calls from the air take off, airlines may need to mandate technologies such as noise-canceling headsets that block out the racket on board and encourage talking at normal volumes. Stan Deal, vice president, sales and marketing operations, at Boeing Commercial Aircraft, says the headset rule has come up in the discussions Boeing regularly holds with airlines about the social impact of in-flight Internet access. Airlines could decide to block voice traffic over their Internet connections, though Boeing says none of its Connexion partners have done that.

Sir Richard Branson, chairman of Virgin Group, offers a clever suggestion for minimizing disruption from voice calls and other uses of the Internet. Sir Richard, whose company operates airlines (including Virgin Atlantic Airways) and cellular service (Virgin Mobile), proposes something akin to the Snooze Zone on current Virgin flights, where the lights on the front of a plane or its top deck are kept dim and food service is limited to allow better sleep among passengers.

He says, via email, that it's worth exploring the idea of a communications zone on planes for people who want to make calls or conduct videoconferences.

Virgin Atlantic is exploring whether to offer high-speed Internet service on its planes. Still, Sir Richard says he's ambivalent about email and phone calls intruding on air travel. "I'm very torn on this, and from conversations I've had with many of our passengers, so are they," he says.