Fighting Terrorism With Cable Telephony


As cable television operators have moved into the delivery of new services over the past decade, they inevitably have been faced with significant public policy issues that were nonexistent in the days when cable merely delivered programming. The expected large-scale entry of the industry into packet-based telephony within the next several years will be no different, particularly in the wake of the Sept. 11 terror attacks on the United States.

Within days of the attacks on the World Trade Center and the Pentagon, as information unfolded about the breadth of the terrorists' planning, it became clear that more aggressive ways to monitor voice traffic on the nation's telephone lines would be necessary to limit the risk of similar assaults in the future. So long as the nation is vulnerable to terrorist activities, cable operators need to be prepared for that challenge and to implement voice technologies that are in the national interest.

Current large-scale voice providers, principally AT&T Broadband and Cox Communications Inc., have deployed "primary line" services that emulate the incumbent services. The service, designed to be the main voice connection to the home, relies on an overlay of proven circuit-switched technology and is fully compliant with existing regulations, including those for the provision of such mandated services as legal wiretapping.

Real concerns arise with the development of packet voice technologies. Those implementing a distributed approach for voice over Internet protocol necessitate the creation, deployment and integration of an additional element simply to implement wiretapping provisions.


Even before "Homeland Security" became a Cabinet-level post, lawmakers recognized the impact that advanced, switch-based telephony features like call forwarding and conference calling could have on law enforcement agencies.

The U.S. Congress passed the Communications Assistance for Law Enforcement Act (CALEA) in 1994 to encourage telecommunications service providers to implement a standard for making telecommunications of all methods more easily accessible to legal electronic surveillance. They were given four years — until October 1998 — to develop systems. In 1997, the Telecommunications Industry Association adopted a standard communications messaging protocol for telecommunications intercepts: the J-STD-025.

At its essence, CALEA provides for the interception and delivery to law enforcement agencies, in real time, call identification and content information about all calls originating from and terminating at a subject, including calls forwarded or redirected by the subject's service. The act also enables agencies to be notified when the subject under surveillance uses services like call forwarding, call waiting, call hold and three way calling, or when a network message that provides call ID information is generated or sent by the intercept access point switch to a subject under surveillance. Finally, CALEA protects the privacy of an interception and against the unauthorized acceptance of communications.


For cable systems that have implemented circuit-switched technology, CALEA is a simple proposition. In circuit switching systems, the content and signaling information of all calls is directed from the calling station to the servicing switch. The circuit-switch is a natural central point where call signaling and traffic are brokered to the required destinations; this includes calls that are targets for lawful wiretapping. This simplifies the implementation, deployment and integration efforts needed to operate the CALEA feature.

In a distributed packet-based approach, with voice calls routed between the origination and destination stations, the absence of a central point connecting all these calls together makes CALEA more problematic. These calls can stay within the packet network (on-net calls) or can leave the network (off-net calls) depending on the location of the destination station.

Regardless of the destination of a given call, when CALEA is invoked, all information relative to the call needs to be accessible to the authorized law enforcement agency (LEA). This means that a central LEA connection point will be identified in the network and all call content and information relative to the subject under surveillance needs to make it to the LEA. This centralization of CALEA requires that all elements that make the distributed packet-based network are CALEA aware. This is a very expensive proposition when talking about systems that have been deployed and need to be upgraded to support this capability.

In this distributed approach, a CALEA server is one proposal being implemented to manage CALEA requests and to broker between all elements involved in the call using signaling similar to a call management server. The addition of this server increases deployment complexity. The more elements, the more interfaces to maintain, the more elements to integrate, and the more elements to regression test when the network needs upgrades. In addition, there is the potential that a computer-savvy terror organization could launch a service attack against the CALEA server, rendering it useless at a critical time.


New architectures, such as cable-media switching, address these issues by offering the secure, centralized features of circuit switches within a packet environment. Unlike current distributed VoIP approaches, these new technologies will act as the broker for all calls, including calls that are targets for legal surveillance.

All calls, regardless of destination, come to the central location and then are dispatched or connected to the proper destination — including the CALEA — when lawful surveillance is invoked. This centralization will enable CALEA implementation without costly upgrades to already deployed elements like CMTS and routers.

Equally significant from both a law enforcement and cable point of view, the centralized technology provides a secure point of surveillance that is resistant to service attacks and is compatible with existing CALEA surveillance equipment.

With the availability of CALEA-compatible technology and mindful of the recent violations of our country's security, it is more important than ever that cable operators ensure that all current and future telephony deployments be CALEA enabled. Terror groups already have demonstrated an astounding resourcefulness when it comes to using American technology against the very country that created it. It would be tragic if future plots — and the groups behind them — escaped detection because the perpetrators were clever enough to render these distributed networks useless.

It is likely that the federal government, which already has taken increased steps to monitor voice and data traffic, will increase CALEA compliance for all telecommunications services, but cable has an opportunity to take a leadership position here in advance of the regulators. The Sept. 11 attacks gave all of us pause; for cable, part of that reflection should be on how to offer telephony systems that are in the best "homeland security" interests of the country.