WATERLOO - Among telephone voice-mail greetings, "We can't come to the phone" is a standard.

But in Iowa today, it may not be accurate.

According to a recent federal study, more than one in five telephone customers in Iowa has cellular service only.

According to a report the U.S. Centers for Disease Control and Prevention issued this month, 22.2 percent of Iowa households now have cell phones but no land lines. Only Oklahoma, at 26.2 percent; Utah, 25.5; Nebraska, 23.2; and Arkansas, 22.6, had higher percentages of cell phone-only users.

Stephen Blumberg, senior scientist at the CDC's National Center for Health Statistics and the lead author of the study, said the research indicated that the trend toward dropping land lines likely would continue.

"We certainly know that the growth in the prevalence in wireless is not slowing down," he said. "Nationally, it's been growing by 3 percentage points every year. These figures are from 2007, so, on average, there's probably about 5 percentage points higher."

Whether Iowa remains near the top is unknown, he said.

"There are some demographics that contribute to the relatively high prevalence of wireless-only households," he said. "Young renters are more likely to be wireless only. And, when we rank states by the proportion of households headed by young adults, Iowa is in the top 10. Iowa is also in the top 10 in the proportion of households that are rented and headed by young adults."

Nationwide, about 20 million phone customers, about 17 percent, have forsaken their land lines.

"I think it's a definite trend," said Laura DiDio, principal with Information Technology Intelligence Corp., a Boston-based consulting firm. "There are more and more younger people who are opting to only use cell phones, especially college kids and college graduates who are just starting out. They might move a couple of times over a 12- to 24-month period. They don't want to be tied to that."

The Iowa Utilities Board said it had noticed the trend, although it had no information backing up the CDC findings.

"We did a local voice telecommunications survey in mid-2007 and found the number of wireless connections exceeded the number of wire-line connections for the first time," said Rob Hillesland, an IUB spokesman. "The one thing we can say is we have seen cell phone use has been consistently on the rise in the surveys and reports we've done here."

Glenn Kass, marketing manager, Sprint's regional office in Davenport, said Iowa's rural population explains the preponderance of cell-only usage.

"These folks are probably out and about more," he said.

The economy also may be playing a role, he added.

"I think you're also seeing you've got people who are looking at their costs and realizing (having both) land lines and cell phones is no longer necessary," he said.

The trend has been noticeable at the retail level, said Chole Casber, sales representative at Sprint's store on University Avenue in Cedar Falls.

"It makes more sense than the land line because of the convenience of taking your laptop anywhere," Casber said. "With a land line, you're locked to your desk."

Casber noted that Sprint customers who opt to drop their land lines and pick up cellular service through the company can keep their old phone numbers.

DiDio pointed to versatility as an edge for wireless.

"I think the mobility and flexibility and the fact that they're not just phones helps," DiDio said. "You can take pictures, you can download music, you can play games, you can go online and get news, weather, sports. Can you imagine not having a cellphone for business today?"

Land lines still have a strong role to play in the business, however, Kass said. It's just that service providers may have to adapt to the changing environment.

"They need to be changing the business model, and that means make things more affordable, attractive, etc.," he said. "Land lines aren't going to disappear altogether."

Contact Jim Offner at (319) 291-1598 or jim.offner@wcfcourier.com.