Nearly a quarter of U.S. homes have abandoned land lines and use only a cellphone, U.S. researchers reported on Wednesday.
Fifteen percent of households have standard plug-in phones but almost never use them, the National Center for Health Statistics found.
The NCHS, part of the Centers for Disease Control and Prevention, relies heavily on telephone surveys to gather health information about the U.S. public. The figures also have implications for the mobile telephone industry.
Stephen Blumberg and Julian Luke of the NCHS examined data from surveys of 21,375 households that included 40,619 civilian adults and 14,984 children under the age of 18.
One of every four American homes (24.5 percent) had only wireless telephones (also known as cellular telephones, cellphones, or mobile phones) during the last half of 2009 -- an increase of 1.8 percentage points since the first half of 2009, the report reads.
In addition, one of every seven American homes (14.9 percent) had a land line yet received all or almost all calls on wireless telephones.
The report, available at www.cdc.gov/nchs/data/nhis/earlyrelease/wireless201005.pdf, also found that 23 percent of adults, or 52 million people, lived in households with only wireless telephones.
Nearly half of adults aged 25 to 29 lived in households with only cellphones, the study found.
(Reporting by Maggie Fox; editing by Paul Simao)