"To a lot of consumers who are technology-savvy, it's not a big deal. But there are consumers — senior citizens in particular — who don't feel comfortable or have access who are being penalized," said Audrey Guskey, an analyst who has studied consumer trends for 12 years.

Stockbrokers and banks are part of a growing number of businesses that expect customers to pay more for help from "a living, breathing company representative," Ms. Guskey, a professor at Duquesne University in Pittsburgh, said Wednesday.

Earlier this week, the Atlanta-based carrier added $2 to domestic round-trip bookings — except for those made at its Web site — to offset rising costs for traditional booking methods.

Delta didn't make a public announcement, but informed travel agents in a message posted Monday over the computer reservations system.

The move drew criticism from the American Society of Travel Agents, which represents 26,500 members in more than 170 countries.

"Delta is saying, in effect, we tried to get you to book on the Internet and now we are going to make it hurt to book any other way. Instead of offering an inducement, they are slapping on a penalty," said Joe Galloway, president and CEO of the world's largest travel trade association.

Delta officials declined to comment.

Ms. Guskey said the motivation for a move like Delta's was simply to save money.

"It's easier and cheaper for companies, the less human resources they need. There's also less chance of error," she said. "Those human factors, in a sense, get in the way."

Steve Slade, 28, is among a growing number of people who've noticed the trend.

"I think we're saving banks enough time and money by using ATMs that we should be able to once in a while go into the bank without have to pay $5 a month to talk with a human being," he said from outside a downtown Delta ticket office.

Slade, who works for a telecommunications company, added that he enjoys the ease, convenience and special deals associated with Internet shopping, particularly since customer service has "gotten so bad."

Call for Action, a nonprofit consumer helpline, is hearing more of those complaints, said the group's president, Shirley Rooker.

"The level of frustration we're hearing from consumers has increased in the last two or three years," Ms. Rooker said. "Either people can't get service, or there's a fee attached, or they're unable to get through to a human being."

Even though they're pressed for time, she said, consumers must tell companies when they are not living up to expectation.

"If we don't like it, we have to stand up and protest by taking our dollars to companies that give you what you want," Ms. Rooker said.

Ms. Guskey expects the trend to continue.

"I think it's going to eventually reach the point where people will be charged for the privilege of dealing with a sales associate at a department store," she said.