SIT.TXT

SIT (Special Information Tones) - 6/16/2002
Written by phlux - fraud@HackTel.com


SIT's are often heard whilst scanning. They are the three escelating tones usually followed
by a recording of the sort. "Your call did not go through, please try again later"
Usually they are not very helpful. SIT's are also used by Telemarketing equipment.

ADAD's or Automatic Dialing Anouncement Devices listen for SIT's and they will parse the
dialed number from its calling database as it is not working. (this is how radio shacks
telezapper works. A clean SIT recorded to an answering machine is just as effective)
ADAD's are used by tele-marketing companies, either by stand alone hardware, or with a
computer and a modem. This is usually the setup used by various schools to nark on you
for skipping school.

SIT's can be very useful to a phone phreak.
________
Encoding;

SIT's have an encoding scheme. The duration and frequencies used in this scheme allows
for 32 different possible encodings.

Tones 1 and 2 consist of a Low or High frequency. The third tone is always 1776.7hz for 
easier decoding.

Tone 1;			Tone 2;
Low: 913.8 Hz		Low:1370.6 Hz
High: 985.2 Hz		High:1428.5 Hz

These frequencies should be +/- 1.5% stable in frequency shift and  +/- 0.2% in frequency
flutter. The duration for the first and second tone is either short (274ms) or long (380ms),
and should be stable within +/- 5% of its value. The duration of the third tone is always
long. (380ms)

The duration of silence between tones is not part of the encoding, but it should not be
greater then 4ms. Interuptions of a tone should be less then 1ms for optimal decoding.
The amplitude variation among the 3 tones should not be greater then 3dB.

____________
Announcements;

The duration of silence between the third tone of the SIT and the prerecorded message
should be no more then 300ms, and 400ms for localy recorded messages.

The amplitude of the SIT should be 2dB lower then the annoucement so hand scanning phone
phreaks do not get pissed off and try to own the system.

Announcements try to identify to the user the condition and the respective action to be
taken. Announcement types are as follows:

No Circuit (NC)
ReOrder (RO)
Vacant Code (VC)
Intercept (INT)
Inneffective Other (IO)

__
NC
A No Circuit applies when there is a failure to find a trunk or to calls affected by
Network Management Controls. The call should be tried again later.
__
RO
The ReOrder applies due to; Internal Switching Blockage, Failure to recieve wink on an
interoffice call attempt, Insufficient or mutilated digits, failure to find an available
resource, interoffice signalling link failure, all announcement trunks busy, switching
equipment congestion or protocol errors. The call should be tried again later.
(A ReOrder tone resembles a busy signal, but is twice as fast (120 interuptions per minute.))
__
VC
Vacant Code applies as per the following conditions; Vacant Code, Unauthorized CAMA '1' or
'0' plus unauthorized code (??), Nonworking 911, Out of area, terminating end office or
tandem recieves digits for nonsubtending code, no route to specified transit network, or
no route to destination.

The following announcement should tell the user that the call could not be completed as
dialed and any specific instructions for an encountered condition.
___
INT
Intercept applies when the number has been changed, vacant number, disconnected number,
non-working number, temporarily suspended service, incoming call restriction.

The announcement should specify the reason for faulty call completion and any instructions.
(this number is not in service, the new number is 313 333 3337)
__
IO
Ineffective other apply under the conditions; prefix or access code dialing irregularity,
improper initial coin deposit, screened access denial, or any dialing irregularity.

Anouncement should include instructions for proper dialing and wether or not to try the
call again.

______________________
SIT Coding Assignments;

	Tone 1			Tone 2		Tone 3
	Freq(Hz)/Duration(ms)			
NC	985.2 / 380		1428.5 / 380	1776.7 / 380
INT	913.8 / 274		1370.6 / 274
VC	985.1 / 380		1370.6 / 274
RO	913.8 / 274		1428.5 / 380
NC*	913.8 / 380		1370.6 / 380
RO*	985.2 / 274		1370.6 / 380
IO	913.8 / 380		1428.5 / 274
*interLATA call handling

_____________
Contemplation

This information can be used by hand scanners for more conclusive data.

It would be interesting to see a small box with the ability to decode SITs in realtime.
Computer software may be the easier solution however, perhaps a wardialer feature.

I think this information is best suited for hand scanners as many announcements are vague.
Also it may be possible to identify certain characteristics of the SIT generated at the far
end by the silent intervals. Needless to say my next scan will include decoded SIT's.

shouts to Lucky225 for schooling me on SIT back in the day, theclone, psyko, cyb0rg/asm
and the HackCanada crew, pbang, dawson, RT, PoT. You guys keep it real.

sksk.