Emergency Communications Technician, Mike Salazar takes 911 calls at the Emergency Communications Center in Arlington, Va. The facility has been updating in order to take on digital emergency calls. (Matt McClain/THE WASHINGTON POST)

As the “East Coast Rapist” attacked two of her friends in the woods in Prince William County, the teenager knew that if she tried to make a call from her cellphone, the man would hear her voice and things would get even worse. But she had to get help.

She pulled out her cell and started thumbing.

“911 . . . pls noww man with gun,” she wrote in a text message. The urgent plea went out to her mother, father and four friends. But emergency dispatchers at the 911 call center never got it. The emergency line is not equipped for text messaging.

The growth of technology has left 911 behind. Although people can send a text to vote for the next American Idol, they can’t send one to report the East Coast Rapist in Prince William or anywhere else.

Modernizing 911 has taken on renewed urgency as the 10th anniversary of the Sept. 11 terrorist attacks approaches, but actual progress is slow and could be years away in many places. That has prompted questions about how much improvement there has been in public safety communications in the past decade.

Federal and local officials readily acknowledge the need to modernize 911 calls, and they have taken small steps to digitize, but there are no plans in place for how to pay the billions of dollars the upgrade will cost and no timetable has been set.

“The thinking is, ‘I can text almost everyone — why can’t I text 911?’ ” said Jeffrey Horwitz of the Arlington County emergency communications center, which recently completed a $38 million upgrade in anticipation of moving to a digital 911 network. “We need to evolve as the technology evolves.”

Consumer expectation has already outpaced 911 capabilities. When Verizon Wireless customers send a text message to 911, they get this reply: “Please make a voice call to 911.” Other simple actions, including sending 911 a smartphone photo of a car speeding from a robbery, are also impossible.

For decades, almost all of the calls to the nation’s emergency number came from land lines. But now, about 70 percent of the 240 million 911 calls received each year come from wireless phones, according to the Arlington-based National Emergency Number Association.

The Federal Communications Commission, which regulates the 911 number, has taken some steps to improve the system. It asked for public comments on a digitized 911 and is reviewing those comments. FCC officials say they plan to propose rules this year on how to begin the upgrade.

“The shift that we need to make from analog to digital 911 is by far the most important change in 911 since the invention of 911,” said FCC Chairman Julius Genachowski, who was an emergency medical technician in college. “There’s a gap between what ordinary people do with technology and the capabilities of our emergency response network.”

After the rules are approved, municipalities could move to the new system on their own, but only as fast as their equipment and budgets will allow. That means that some places will have digital 911 faster than others, and some places might never get it.

Gordon Deans, executive director of the Maryland Emergency Number Systems Board, said the board has bought digital-enabled phone equipment for counties that can receive texts, photos and videos.

“We would need to install new software, train staff, and get some more equipment to handle and store that data, but we could make the transition very quickly — in a few months,” Deans said. The state board would share its investment with local jurisdictions to ensure continuity across the state.

In the District, the emergency communications recording system will be digital-ready as part of a $55 million radio upgrade this year, said Teddy Kavaleri, interim director of the Office of Unified Communications. “That means that after the national standards are set and we’re ready to upgrade, all we have to do is purchase some add-on software. Then whether it’s a radio transmission, a phone call, text or other data, we can store it and play it back,” he said.

Virginia has three pilot projects underway for 911 digital upgrades, said Dorothy Spears-Dean, public safety communications coordinator for the Virginia Information Technologies Agency.

But changes to the nation’s emergency number system could bring a host of legal issues. What kind of regulations, if any, would Congress need to enact to support the transition? Text messages, which are widely used as a social tool, don’t have any location information tied to them. If a text message to 911 is delayed and someone dies because of a lack of assistance, who is legally responsible? Emergency officials say there is no substitute for speaking to a trained 911 operator.

And who will pay for the new system? The cost of upgrading 911 across the country over the next 20 years could be $9.1 billion, according to a 2009 Department of Transportation study.

The future of 911 can be seen in a pilot emergency-text-message program in Black Hawk County, Iowa. It has been available to subscribers of a particular local wireless company since 2009, said Judy Flores, administrator of the county’s 911 system.

The service receives about a dozen emergency texts a month. Some turn out to be life-saving. In one instance, Flores said, the ex-boyfriend of a homeowner violated a restraining order and broke in. The woman texted 911, and police arrived and made an arrest.

Situations in which a text message might be safer or more effective than a phone call play out across the country almost every day.

Virginia Tech students frantically texted 911 as Seung Hui Cho opened fire on campus in 2007. The texts went nowhere, according to a study by the 911 Industry Alliance.

Since the mass shooting, Virginia Tech has sought to make changes to its 911 system. The campus will be part of a new regional public safety authority that will handle all police and fire emergency calls, which four dispatch centers have done. The consolidated center will have the latest digital technology and is set to open in 2015.

Until then, and elsewhere across the country, the need for digital 911 remains.

The Prince William teenager sent her text at 9:05 p.m., and the first call to 911 came from the girl’s mother six minutes later. Once police got the 911 call, it took them just two minutes to get to the scene — eight minutes after the girl’s initial text to family and friends.

Officers rushed into the woods. That Halloween night in 2009 was the closest police would come to catching the perpetrator of 12 attacks over 14 years along the East Coast until a suspect, Aaron Thomas, was arrested last month. But that night, the attacker got away.

Staff writers Maria Glod and Josh White contributed to this report.