On Thu, Jul 27, 2000 at 02:20:26AM -0400, !Dr. Joe Baptista wrote:
> Hello:
>
> I'm looking for a list of telephone company modulation frequencies used on
> toll lines (trunk lines) to control switching between offices. Anyone
> know where I can find them. Used to know them by heart - 2600 to disconect
> and 300 - 1200 ?? for the control tones.
>
> Joe Baptista
>
In band signalling (tones on the trunk lines) is no longer in
use in the USA to any important degree and hasn't been since the late
70s or so. Control of call setup and supervision is handled by an out
of band packet network using a signalling protocol called signalling
system 7 (SS7) running over entirely separate data circuits which often
don't even take the same paths through the network as the trunk groups
they control do.
But what you are looking for is the CCITT signalling system #5
or the Bell MFKP (multifrequency key pulsing) tone set (different than DTMF,
the touch tone tones). Also commonly known as the "Blue Box" tones.
The US frequencies were 700, 900, 1100, 1300, 1500, 1700 sent in pairs.
But what this has to do with cryptography and the politics of privacy
I am apparently too dimwitted to see...
--
Dave Emery N1PRE, [EMAIL PROTECTED] DIE Consulting, Weston, Mass.
PGP fingerprint = 2047/4D7B08D1 DE 6E E1 CC 1F 1D 96 E2 5D 27 BD B0 24 88 C3 18
