My understanding is that the "c-tone" is the same as that generated by the "C" button of the A-B-C-D/FO-F-I-P column found on old DoD precedence-equipped touch-tone AUTOVON phones. The C or I (for "Immediate" precedence) button delivers a DTMF pair of 852 and 1633 KHz. Ping me off net for some AUTOVON phone pics.
Mike snipped-for-privacy@bah.com
From: snipped-for-privacy@hallikainen.com
> Subject: Security Flaw Allows Wiretaps to be Evaded, Study Finds
> This is the first I'd heard of the "c-tone'.
> Harold