A few days back David S. Bennahum talked to three VoIP service providers regarding CALEA. He got three different, not altogether surprising, responses. That column raised more questions than it answered. I wish he had done some more follow-up.
Citron of Vonage says that there are two limitations on LEAs: they “can listen in on phone calls only in real time. They are not permitted to record calls and play them back later to check for incriminating information.” There is no mention of either of the limitations in the web site Bennahum quotes. I wish he had clarified this further with Citron or talked to some CALEA experts. He further quotes Citron that the intercept can be done only in “analog-friendly wires”. It must be a wrong translation. Most of today’s PSTN facilities are digital and tapping seems to be routinely done.
Time Warner is fully willing and capable to allow LEAs to tap calls in their system. Bennahum seems to suggest that it is because CMTS is a convenient tapping point. But he fails to ask TW regarding the limitations identified by Citron. It seems to me that against these two limitations, ability to tap is a moot point.
More than a week back, there was another article discussing the same issue. There Pulver was quoted as saying that "I'm also not sure how some of these providers are going to meet CALEA." Since all service providers can provide call identification information, I suspect the problem is giving access to the content. But, almost all service providers use Session Border Controllers to address NAT traversal problem. So if the media need to go through an SBC, then tap could be placed there (assuming that Citron’s limitations are not valid). Indeed some of the SBC vendors suggest as much.
That brings us to Skype’s response. They say that they do not have access to neither call identification information, nor the content. I agree that this is true, because they are not a carrier. They produce a product. But they also say that their application encodes the content and so difficult to decipher, even if it could be tapped. Then consider the following scenario: Somebody builds Skype like application, running on two computers connected to each other through a dialup connection. The call is now going over PSTN, still it can not be meaningfully tapped. Shouldn’t we be scrapping CALEA altogether? I hope not.
Posted by aswath at February 23, 2004 06:25 PM