Amanda Lee of Cambridge received a call from Comcast Corp. in December ordering her to curtail her Web use or lose her high-speed Internet connection for a year.
Lee, who said she had been using the same broadband connection for years without a problem, was taken aback. But when she asked what the download limit was, she was told there was no limit, that she was just downloading too much.
Then in mid-February, her Internet service was cut off without further warning.
For Lee and an increasing number of people, a high-speed Internet connection is a lifeline to everyday entertainment and communication. Television networks are posting shows online; retailers are lining up to offer music and movie downloads; thousands of Internet radio stations stream music; more people are using WiFi phones; and "over the top TV," in which channels stream over the Internet, is predicted to grow.
That means that more customers may become familiar with Comcast's little-known acceptable-use policy, which allows the company to cut off service to customers who use the Internet too much. Comcast says that only .01 percent of its 11.5 million residential high-speed Internet customers fall into this category.
"Comcast has a responsibility to provide these customers with a superior experience and to address any excessive usage issues that may impact that experience," Comcast spokeswoman Shawn Feddeman said in a statement. "The few customers who are notified of excessive use typically consume exponentially more bandwidth than the average user."
Feddeman declined to say where Comcast draws the line on too much Internet usage, instead saying the amount of data that could trigger a warning call would be roughly the equivalent of 13 million e-mail messages or 256,000 photos a month. Although those files vary in size, a typical photo file size is 1 to 2 megabytes, meaning that excessive users are downloading hundreds of gigabytes per month.
Matt Davis, a research director at IDC Corp., said that because of the way cable high-speed Internet works, a person using a huge amount of bandwidth will slow service for hundreds of customers.
"You look at it and see there's some two to three people in the neighborhood or a college dorm . . . and what they're doing is impairing the customer experience for the rest of the people off that node," Davis said. "Then it's a business decision: Do you alienate a small percentage of customers to make your other customers happy?"
Davis said that even if only a tiny fraction of customers are downloading enough to trigger the policy, that will probably change as more entertainment moves to the Internet. Today, he said, an average subscriber downloads about one gigabyte per month, but even if everyone on the network began downloading just one movie a month, it could have a dramatic effect on the network.
Downloading is "certainly going to increase dramatically over the next five years," he said. "And even if it's double or triple or quadruple, it's going to place a lot of pressure on networks that are being pressured right now."
Limiting Internet use to maintain good service for everyone is common among providers, and Comcast says it does not disclose a hard-and-fast limit because numbers would shift as the network evolves. But the policy contrasts with Comcast's marketing, which emphasizes download speeds and touts its PowerBoost service, which gives customers an extra surge of speed when downloading large files.
"If Comcast has that limit, they really need to say what that is," said Frank Carreiro of West Jordan, Utah, who said he contacted customer support via an online chat after his family got a phone call warning that they were using the Internet too much. The customer representative said there was no official limit; the family's service was shut off in January.
"It's like if you're driving down freeway, and there's nothing to say what the speed limit is," Carreiro said.
It also seems to be something that the company's own customer support representatives are unfamiliar with, according to three people who were recently kicked off Comcast Internet service.
Lee said that she was not given specifics about how much to reduce usage and that when she called customer support to get more information about the warning, the customer service representative suggested that it may have been a prank call.
Joe Nova in Attleboro said a Comcast representative called in June to inform him that he was downloading too much content and must stop immediately or lose Internet service for a year.
When his service was cut off, he called customer support. "I told them I was willing to sign up for a professional account, a business account, and they said they never heard of a bandwidth limit," he said.
Nova, Lee, and Carreiro admit to activities that devour bandwidth, like downloading movie and television shows, listening to Internet radio, or making video calls. But they also said they weren't given clear guidelines about how to remedy the situation and were told repeatedly that there was no download limit, even though they were warned that they were downloading too much.
Acceptable use policies that state that consumers cannot download so much content that it degrades service are common among Internet providers.
Although Richard Ramlall, RCN senior vice president of strategic and external affairs, said in a statement that the company "does not suspend service related to the frequency or size of downloads," RCN's policy says customers cannot "act in a manner that negatively affects use of the Internet by other subscribers, users, individuals, or entities."
Verizon's DSL service has a different network architecture that means a single "bandwidth hog" should not affect neighbors and does not limit downloads, according to spokesman Mark Marchand.
"Legitimately, everybody's going to be a bandwidth hog sooner or later, because that's what the Internet is, going forward," said Linda Sherry of Consumer Action.
Carolyn Y. Johnson can be reached at email@example.com.