Nick Milos, manager of corporate facilities at the Port of Seattle, said he has tested the system and found 19 of 20 policy makers responded in 15 minutes, up from the two hours it sometimes took to get a response using the old system.

The service does not communicate with the 800-MHz public safety band of devices, including two-way radios carried by police and fire fighters, Hayden noted. "But if you have an emergency and want to tell everybody very quickly, this does that and very reliably," he said.

Although Hayden said he could try to notify a group via an e-mail blast, "I wouldn't know if they got the e-mail."

The hardest part of using the service was adding the names of those receiving messages into the system, Hayden said. But it's very easy to keep contact information up to date, he said, since users are responsible for contacting the service and saying which group of devices should receive the messages.

The port's alert service fills a gap apparent in some emergency response systems, said Tole Hart, an analyst at Gartner Inc. Though it would not be as useful for responders at the scene of a crisis, it could help with interoperability at a central command center, he said.