> Also, it probably goes via a different physical path. And at least some > SS7 trunks are encrypted with DES. Care to say anything about which ones are encrypted and why? Or to ask it another way, who decides? I phrased it that way because I'm not certain of the extent, and I'm not certain how much of what I know is AT&T-proprietary. But the obvious risks that encryption avoids are traffic analysis by enemies (pick your own definition of enemy), information on what channels to wiretap (remember the furor a few years ago about the location of the then-Soviet embassy on a hilltop in Washington, D.C.?), and the threat of phone-phreaking by introducing bogus call setup messages. On the latter point, recall that out-of-band signaling was introduced in part in response to ``blue boxes'' and other device that exploited in-band signaling technologies.