The Homeland Security Department may have found one of its holy grails in its mission to protect the country: a way for all its equipment — and the equipment of every other law enforcement and first responder agency — to communicate with one another.

Agency officials plan to make an announcement this week in Dallas about the implementation of new software that lets existing and new communications equipment interoperate securely.

The new protocol is designed to overcome the communications difficulties that plagued first responders during the Sept. 11, 2001, terrorist attacks. Police, firefighters and other first responders were often unable to communicate because of differences in the equipment they used, which contributed to the deaths of some firefighters in the World Trade Center.

The Cryptographic Overlay Mesh Protocol (COMP) allows radios, mobile phones, laptop computers and other equipment to communicate with one another, said Mark Tucker, chief executive officer of CoCo Communications, which developed the protocol.

COMP connects land-based telephone lines, radio systems, wireless networks, satellite transmissions, peer-to-peer networks and mobile phone systems, Tucker said. Through proxy programs, it is also "100 percent backward-compatible, back to analog," he said.

DHS has a strong interest in the project, said Kerry Thomas, director of national preparedness programs in DHS' Office of State and Local Government Coordination and Preparedness.

The department's Information Technology Evaluation Program, which cultivates promising information-sharing technologies, provided a $979,100 grant to pay for a pilot program in Dallas.

The Dallas Love Field Wireless Integration Project will connect all law enforcement agents and first responders who cover the city's airport. The project will serve as a model for eventual statewide and national adoption of the technology.

Users praise COMP for its security, flexibility and seamless operation with existing equipment. "It has worked great," said Lt. Michael Doyal, project manager for the Boarding Team Communications project at the Coast Guard's Research and Development Center in Groton, Conn.

For the past year, Doyal has used the protocol to help Coast Guard teams that board vessels better communicate with their ships. "Regular VHF doesn't work below deck too well," Doyal said, but COMP enables Coast Guard personnel to maintain 100 percent wireless connectivity.

The protocol permits the Coast Guard to use its existing radios to share information with its port partners, Doyal said.