-By Adweek Staff

NEW YORK More than 20 million U.S. telephone households, roughly 17 percent of the nation's total, reply solely on mobile phones for home telecommunications, according to a new study from Nielsen Mobile.

The research suggests that one in five U.S. households could be wireless-only by year's end.

It's probably no surprise that consumers' desire to trim household bills is driving the trend.

"Landline-wireless substitution may just be the start," said Alison LeBreton, vice president of client services for Nielsen Mobile. "As wireless data networks improve and speeds become more and more competitive with broadband, some consumers may cut the Internet cord, as well, favoring wireless data cards and other access through carrier networks."

Other key findings:

-- U.S. "cord cutters" tend to have lower income levels -- 59 percent have household incomes of $40,000 or less.

-- Smaller households, with just one or two residents, are more likely to cut the cord than larger households.

-- Moving or changing jobs are the biggest life events associated with cord cutting: 31 percent of cord cutters moved prior to eschewing landlines and 22 percent changed jobs.

-- Wireless adopters tend to use their mobile phones more than their landline peers, 45 percent more per phone, but still save an average $33 per month.

However, wireless substitution doesn't work for everyone. Ten percent of landline phone customers have experimented with wireless-only in their household, but then returned to landlines. Nielsen found that needing a landline for other services (satellite TV, pay-per-view, etc.) is the primary reason people mend the cord.

Adweek is a unit of the Nielsen Co.

The paper is titled "Call My Cell: Wireless Substitution in the United States."