IETF eyes 'Net emergency communications

System would route urgent calls over Internet much as 911 telephone network does now.


The IETF has kicked off an effort to develop communications protocols needed to support emergency communications over the Internet.

The new IETF working group is called Emergency Context Resolutions with Internet Technologies (ECRIT). ECRIT is looking for a way to route emergency calls over the Internet similar to the way in which 911 calls are routed over the public switched telephone network (PSTN).

If successful, ECRIT would have a significant effect on service providers, including traditional wireline and wireless carriers, ISPs and start-up VoIP providers, because they would need to upgrade network hardware and software to support any new system.

Universal standards

"The ambition of this working group is to provide a universal solution for a particular part of the emergency communications problem," says Jon Peterson, an engineer with NeuStar who serves as the Transport Area director overseeing ECRIT. "We are looking at how, based on the context of an emergency call, to route it to the right emergency call center."

ECRIT is not addressing prioritization or pre-emption of emergency calls, which is available in many government and military telephone systems. Instead, the IETF's Internet Emergency Preparedness working group is handling those issues as it develops an overall architecture for communications systems used for disaster recovery.

"We're looking at the consumer, 911-class problem over the public Internet," Peterson says.

Because it addresses this broader need, "ECRIT is the most important protocol work going on in the IETF related to emergency communications," he says.

The IETF announced the ECRIT working group in February, and ECRIT held its first meeting March 9 in Minneapolis.

The PSTN has been configured to recognize specific numbers such as 911 or 112 as calls for emergency services. These calls are sent to special call centers that handle emergency response. These emergency calls are associated with the physical location of the call originator so they can be routed to the appropriate emergency call center.

With its many overlay networks and tunneling mechanisms, the Internet is a more challenging infrastructure for building an emergency communications system than the PSTN, IETF participants say. The ECRIT working group is trying to define the requirements of Internet-based emergency calling and to select appropriate technologies for describing the location of the call originator and managing the call routing.

Video, text messaging service

ECRIT is focused on VoIP calls, but the group's charter says it also will consider the use of video or text-messaging communications to request emergency services.

Hideki Arai, an engineer with the Oki Electric Industry in Japan, said the new system "must be equivalent to traditional emergency calling . . . and it must be easy to migrate from the PSTN to the Internet."

Arai briefed the working group on an ongoing Japanese government effort to outline its own requirements for emergency calling with IP telephony services.

Brian Rosen, president of start-up Emergicom, says the Internet emergency calls also need to be traceable in case something goes wrong. "You need to know what happened to a call," Rosen says. You also need a call-back mechanism in case the caller hangs up, he adds.

Challenges loom

Participants in the ECRIT working group agree that building an Internet-based emergency communications system is a challenge.

"One of the hardest things is how much do we worry about being backwards compatible," said Henning Schulzrinne, a professor of computer science at Columbia University who outlined several requirements for emergency calling using Session Initiation Protocol.

The Internet’s 911

Core requirements for an Internet-based emergency communications system include:
Identifying and validating emergency calls so that all carriers along the call path know it is an emergency call.
Determining the location of calls.
Routing calls to an appropriate emergency call center.
Protecting against spoofing.

The ECRIT system also needs redundancy and reliability.

"You need to have congestion control everywhere because when bad things happen lots of people make emergency calls," Rosen says.

The ECRIT working group seems to favor using protocols developed by another IETF working group called Geographic Location/Privacy to fetch and deliver location information to its emergency call routing system.

The ECRIT working group's first milestone is to develop a document that defines the terminology involved in emergency communications over the Internet and lay out the requirements necessary for the system. The group says it hopes to have this document completed in April.

After that, the working group has set an aggressive timetable for its work. It plans to complete a document outlining security considerations in April. By August, the group intends to complete three documents: one on setting up communications sessions between callers and emergency response centers; another on associating sessions with physical locations; and a third on routing emergency calls based on location information.

Peterson says he's optimistic that ECRIT can meet its schedule. "At the meeting, we had many different groups presenting that represented Japan, Europe and North America, and they all outlined the same core requirements," he said. "That was very heartening."

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