Linda Clausen really wants to end her six-year history as a Cingular Wireless customer, but she's bound by a contract until August, she says. It would cost her at least $150 to break her two-year contract.

"I've already spent enough," said Clausen, a social worker who said she's angry because she gets poor service near her Chevy Chase home, and she paid $250 for a phone that doesn't work. "I don't want to spend another penny."

There are plenty of consumers like Clausen who would love to count themselves among the 3.3 million mobile-phone users who've switched carriers and kept their phone numbers but are held back by long-term deals. Most analysts estimate that well over 80 percent of cell-phone users are under a contract and would have to pay hefty fees to leave their existing provider.

This helps explain why, nearly six months after the start of a rule allowing mobile-phone users in the top 100 cities to keep their numbers when switching carriers, far fewer than the tens of millions initially anticipated have taken advantage of the rules.

On Monday people in the rest of the country will be able to switch wireless carriers and keep their phone numbers. If the first phase is any indication, there will not be a mad rush but a gradual shift.

One of the reasons there have been far fewer participants is that cell-phone contracts can be confusing, consumer groups say.

"I think there is a lot of confusion as to how contracts work," said Janee Briesemeister, campaign manager for EscapeCellHell.org, a project of the Consumers Union. Every time customers change calling plans or upgrade phones, companies usually require them to renew their contracts, she said.

Before Nov. 24, when the number-switching rule went into effect, many cell-phone companies made a big push to lock in customers by offering rebates for new phones, discounts on plans or even bonus frequent-flier miles.

"I think the industry did a good job in the six to eight months prior [to the new rule] . . . so it wouldn't be this mad rush" to switch providers, said Terry Addington, president and chief executive of First Cellular of Southern Illinois, based in Mount Vernon, Ill. The small mobile-phone carrier invested $1 million to upgrade its systems to allow number transfers and so far has wooed about 350 customers and lost 250.

Also, many customers may have been scared away by tales of software glitches that meant switchers had to wait weeks or even months to get their new service, said analysts.

"It was probably one of the most publicized technology failures, so people heard stories and people said, 'I don't really need to do this,' " said Roger Entner, an analyst with the Yankee Group, a Boston-based market-research firm.

Steve Gasque, a Bethesda resident and a real estate agent, said he tried to switch his carrier from Nextel to Sprint, expecting the switch to go through in several hours. Instead, it took a month an a half, he said.

"Every other day, I'd be on the phone with customer service, and every day I'd get a different answer" for what was holding up the transfer, he said. He said he ended up paying both carriers during that period.

Such experiences were commonplace during the first two months; the Federal Communications Commission received nearly 5,000 complaints from consumers about their experiences, ranging from long delays to billing errors that resulted from trying to switch carriers. Between mid-March and mid-April, the total number of complaints dropped to about 400.

"The most surprising thing was the lack of preparation on the part of some major carriers. It takes two, right? So the process only works as well as the weakest link," said Pat Devlin, regional president of Verizon Wireless.

During the first two months, the most complaints -- 1,221 -- concerned AT&T Wireless Services Inc., which had problems with its new customer-relations software. It lost 367,000 subscribers during the first quarter, while the rest of the industry posted gains. In January, it put itself up for sale and struck a $41 billion deal to be acquired by Cingular Wireless LLC.

"The biggest impact [of the number-transfer rule] was that AT&T Wireless died," said Entner. Verizon Wireless, T-Mobile USA Inc., and to a lesser extent, Nextel Communications Inc. gained customers from other carriers, he said. The other carriers managed to hold on to the bulk of their customer base, he said.

Rural consumers could well experience problems when carriers in those areas start allowing their customers to switch numbers, said Travis Larson, a spokesman for the Cellular Telecommunications & Internet Association. Many rural carriers will be doing transfers manually, or via faxed requests, because they can't afford the complex software systems some of the bigger carriers have, he said.

But some carriers, like AT&T Wireless, expect the next phase to go more smoothly. "Now, we have six months of experience porting with other carriers. We believe that we're ready for this next round of numbers," said Rochelle Cohen, spokeswoman for AT&T Wireless. Software glitches and other problems "are largely behind us. We did encounter some challenges in the early days." Now the company is telling customers who want to switch that the process will take less than six hours.

But the barrier many customers in the Washington area seem to mention most frequently is their long-term contracts.

Wendi Betts, an Arlington hairstylist who says she gets poor reception on her Sprint phone, wanted to switch to Verizon Wireless months ago. But said she waited until her contract expired on May 13 because Sprint customer service told her it would cost her $200 to break her contract, and she decided "it wasn't worth it."

Likewise Connie Collins, a secretary at a Washington law firm, plans to switch Monday when her year-long contract with T-Mobile expires. The plan she shares with her 22-year-old son always runs over the 600-minute limit, she said.

"You know how the kids like to do the text messaging. My bill comes to $130 a month," she said with exasperation. But she's not willing to pay the $200 it would cost her to end her contract early, and she wants to keep the cell-phone number that's printed on her business cards, she said.

As Woodbridge resident Charles Butler stood in front of the Verizon Wireless counter at the Pentagon City Mall earlier this week, the Arlington County sheriff's officer scrutinized the contract. He said he is considering upgrading his old "dinosaur" cell phone for free in June when his contract is up. But the company will require him to sign a two-year contract to do that.

Right now, that makes him wary. "If someone comes up with something better than what Verizon has, I want to be able to switch," he said. "Two years is a long time to have a cell phone plan."