Is the End of Unlimited Internet Near?

"If they are going to behave like a utility, shouldn't they be treated like one?" he added.

He also argued that even though a 250 GB bandwidth cap is generous in today's terms, it may not be sufficient in the future, especially as bandwidth-needy, high-definition video becomes more common.

In its announcement, Comcast said its average residential customer uses approximately 2 to 3 GB. To put its monthly limit of 250 GB in perspective, the company said that to consume that much bandwidth a customer would have to send 50 million e-mails, 62,500 songs, download 125 standard-definition movies or upload 25,000 hi-resolution digital photos.

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Comcast spokesman Charlie Douglas told ABCNews.com that the company has had an excessive use policy for years but has never disclosed its definition of excessive use.

When the customers would exceed the limit, he said Comcast would call to alert them. In most cases, the customer would voluntarily moderate his or her usage in response. If customers didn't cut back on usage, Comcast reserved the right to suspend service. Douglas said the only difference in the policy is that customers now know that the threshold is 250 GB per month.

He says Comcast does not provide a meter tool because free and fee-based meter tools are readily available and not necessary for 99 percent of their consumers.

Although Douglas says that the company is evaluating usage-based billing models that resemble Time Warner's trial program, he stressed that this cap is different.

"This is about protecting the 99 percent of people who don't use a massive amount of bandwidth from the small percentage that does use an extreme amount," he said.

But industry experts observe that Internet technology is advancing rapidly and the lack of good data make it difficult to prepare for the future.

"Today's bandwidth hog is tomorrow's average user," said Fred Von Lohmann, a senior staff attorney for the Electronic Frontier Foundation, a nonprofit civil liberties group. If a cap had been imposed on the top 10 percent of Internet users in 1997, many Internet innovations of today would likely not exist, he said.