More than 20 million homes have cut the cord on landline phones

More than 20 million U.S. households -- 17% of all homes with phones -- use only a cellphone, according to Nielsen. That figure has quadrupled since late 2003, when only 4.2% of households were wireless only. "As wireless network quality improves and unlimited calling becomes increasingly pervasive, we expect the trend toward wireless substitution to continue," Alison LeBreton, vice president of client services for Nielsen Mobile, said in a news release. "In a tightening economy every dollar counts, and consumers are more and more comfortable with the idea of ditching their landline connection." Young people are more likely to use only a wireless phone. And the majority of people who have dropped their landline service are in lower income brackets, according to the Nielsen report. Cutting costs appears to be a big reason for cutting the cord. A landline phone costs an average of $40 a month. But going wireless-only doesn't mean you can pocket all those savings. "Wireless substitutors" use their cellphones more, paying an average of $6.69 a month more than people who also have a land line, Nielsen said. Those increased wireless charges are one of the reasons people give for returning to landline service. About 10% of households with a landline phone in the second quarter of this year relied only on a cellphone before.