BlackBerrys make e-mail portable, available any time and almost anywhere. Airline delays become office time. An elevator ride becomes a chance to dash off a reply. A companion's restroom trip at a restaurant provides just enough time to close a deal electronically.

The pocket-size devices have created a borderless world of new opportunities for multitasking. BlackBerrys, and a growing number of cell phones like them that come with tiny keyboards, have made it easier and more tempting to sneak in work during personal time and personal messaging at work.

But as instant e-mail devices accelerate the cadence of work life, there are increasing complaints that they whittle away at time that people once used to give, undivided, to family or co-workers, or to find solitude on the beach or during the daily commute.

E-mail on the go also has raised new questions of electronic etiquette. Most people have learned to shut off their portable phones or set them to vibrate silently during business meetings and social events. There's no such consensus yet on proper behavior for those who silently, relentlessly, punch out BlackBerry messages with their thumbs.

In a recent survey by Harris Interactive commissioned by wireless provider T-Mobile USA Inc., 15 percent of wireless-device users said they have e-mailed from a restroom, 19 percent while eating in a restaurant, and 21 percent while talking to friends or family.

BlackBerry, introduced in 1999, is the most prominent example of a broader wireless e-mail phenomenon. About 1.6 million BlackBerrys are used in the United States, according to the maker, Research in Motion Ltd. of Ontario, Canada. In addition, there are more than 14 million "smart phones" — mobile phones with keypads and Web browsers — among the 169 million cell phones in use in the United States, according to Instat/MDR, a market research company. The firm predicts the number of smart phones will increase 44 percent a year over the next five years.

At $200 to $500 for recent models, plus monthly connection charges of about $40, BlackBerrys, Treos and other devices are still used mostly by highly paid professionals. Through wireless carriers, Research in Motion sells BlackBerrys to law firms, healthcare companies, real estate agents and government agencies.

Increasingly, wireless e-mail gadgets are being marketed to a broader audience. T-Mobile's flip-top Sidekick is popular among young consumers even though its price approaches that of a BlackBerry. This week, AT&T Wireless introduced Ogo, a $99 wireless device that offers e-mail and messaging service for $17.99 a month.

As prices start to fall, more and more people will use such handhelds as miniature substitutes for their desktop computers, said Neil Strother, a senior analyst with Instat/MDR.

The proliferation seems to have a viral effect — accelerating the general pace of business, compelling others to get things done even faster.

"There's competitive pressure if you're not responsive to e-mail," said Wilhelm, a telecommunications lawyer.

BlackBerrys also have changed the dynamic of many business meetings. Doug Poretz, a public relations executive at Qorvis Communications LLC in McLean, Va., says he often sees employees hunched over, typing below the table. "I have mixed feelings," he said. "If they're checking on client business, that's OK." But for all he can tell, they may be making weekend plans.

In a Washington law office, attorney Chris Rhee often participates in meetings in a conference room walled with thick concrete slabs that block most wireless signals. Around him — in the middle of meetings — attorneys wave their BlackBerrys in the air, trying to catch a stray signal through the window.

Barbara Harsha, executive director of the Governors Highway Safety Association, said that during a droning presentation at one recent conference, she typed an e-mail to a colleague under the table: "This speaker is just awful." When she looked up, the man next to her was doing the same thing.