As a construction coordinator for one of Florida’s biggest home builders, Angela Byrd works under a lot of pressure. Myriad customers, vendors and government officials bombard her daily for information at her DeBary, Fla., office.

Byrd is having an easier time with the pressure these days, thanks to a communication tool that’s old hat to teen-agers but relatively new to the workplace — instant messaging, or IM as it is widely known.

IM beats a phone call or an e-mail by a mile when it comes to getting a fast answer, Byrd said. Using a phone, she would have to call one desk after another until someone answered. Using e-mail, the message might take minutes to arrive, and the recipient might not be there.

But with instant messaging, she can use a contact list on her computer to find out who is working on the computer, send a message and expect an answer in a couple of minutes.

“When you have a customer right in front of you and need an answer right away, you can check for people who are online and IM them,” said Byrd, 35, who has worked for Melbourne, Fla.-based Holiday Builders for the past year.

Byrd still uses her telephone and relies on e-mails for most written communications, but instant messaging has become her lifeline “for priority items, emergencies, when there’s a customer waiting on the phone. It’s nice for information you need instantaneously.”

Byrd’s experience is becoming common in the workplace. “Ninety percent of businesses have some level of instant messaging within them,” said Mike Osterman, whose research and consulting firm near Seattle has closely tracked the instant-messaging phenomenon. Most businesses have just a few IM users, he said, but word is spreading fast.

There’s a receptive audience. Consumer use of instant messaging already is in the hundreds of millions worldwide. Estimates of the number of IM users in the U.S. workplace range from 23 million to 60 million.

Osterman said as of now, about 20 percent of employees who use e-mail also use IM. He predicts within four years, “virtually all e-mail users will be IM users.”

Companies increasingly are paying attention to the IM trend. Most workers who instant message in the workplace do so on consumer networks such as AOL Instant Messenger or MSN Messenger for Windows. “People bring it in from home or download it from the Internet,” Osterman said.

That presents several problems, he explains, including a lack of security, the risk of viruses, an inability to document IMs that contain critical data, and the fact that the system “is not controlled by the company.”

As a result, a growing number of companies are purchasing “enterprise” instant-messaging products that deliver a closed or limited-access system. It’s a hot market, with companies, such as IBM Lotus, WiredRed and Bantu, competing for business.

Some enterprise systems also allow two or more IM users to work on the same document at the same time. Another plus: Given the nagging problem of unsolicited commercial e-mail, also known as spam, enterprise systems make the instant-messaging equivalent, “spim,” virtually impossible.

Spim is now an occasional irritant for those using consumer-grade instant-messaging systems, Osterman said. It will get worse as spammers turn their attention to IM, but enterprise systems will be all but immune because they limit access and do not allow delivery unless the recipient says it’s OK.

According to Osterman, the dawn of the IM trend dates to 1996, when a small Israeli company, Mirabilis Ltd., introduced an Internet-wide instant-messaging system called ICQ (as in “I seek you”). ICQ was purchased by AOL in 1998. That’s when IM “started getting a head of steam,” Osterman said, “and it started with teens.”

Osterman said instant messaging was evolving into a communication tool that goes beyond computer screens. There already are systems that allow IMs to be automatically diverted to an employee’s cell phone or personal digital assistant when she’s away from her computer.

Such a capability, Osterman said, “is like a good secretary who knows how to find you no matter where you are.”