Last week Light Reading hosted a seminar on Session Border Controllers (SBCs), sponsored by four vendors of SBC. One of the presenters made a point that SBC could be used to support CALEA. The idea is that when a call is being established that involves a target, the SBC could force the media to flow through it and the SBC could provide a copy of the stream to the LEA. There is a small problem with this approach.
If the media is exchanged directly between the end-points, the headers in the RTP packets will contain the IP addresses of the end-points, but the intercepted calls will contain the IP address of the SBC. So a target can easily detect whether the call is being monitored or not, violating one of the CALEA requirements. It doesn’t matter whether the latency introduced by SBC is not detectable. So if SBC is used for CALEA, then the media for all the calls must be routed through it. That means, SBC and the network connectivity must be sized accordingly.
Posted by aswath at April 28, 2004 04:24 PM