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Special Information Tone (SIT) requirements

Started by thx1138, August 25, 2016, 11:53:54 AM

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thx1138

I developed some software for myself that monitors incoming calls via a modem, extracts the Caller ID info, and allows the phone to continue ringing or throws a modem handshake at the caller if they are in the list of numbers to be rejected. All of that works fine.

I have one particular caller that is very annoying and I would like to play the "Intercept" SIT tone that indicates the phone is no longer in service at them. I've heard that will cause robo-caller systems to take the phone number out of their database.

I've managed to switch to voice mode on the modem and send the tones but have a question. The info I got from Wikipedia had the following statement: "To minimize the number of callers who may abandon the call without listening to the announcement, the nominal time gap between the third tone segment and the beginning of the announcement is set as close to zero as possible, with an allowed maximum of 100 ms."
https://en.wikipedia.org/wiki/Special_information_tones

I'm wondering if the announcement following the tones is required for the tones to be recognized as Intercept SIT. Right now I'm just sending the tones, waiting 2 seconds, and hanging up. Do I need to tack an announcement on the end for the tones to be recognized as a SIT?

Any help will be greatly appreciated.

dsk

I do not believe so, but usually the message follows pretty close, just to not waste time.  I have made a welcome message at my callcentric account, SIT followed by instructions to call .... This has reduced the number of calls radically. 

dsk


TelePlay

The "disconnected" tones in the sample clip are played twice. Is it necessary to play them twice or will once be enough?

thx1138

You only hear them once at the beginning of the message when you call a real disconnected number.

TelePlay

Quote from: thx1138 on August 27, 2016, 06:47:22 PM
You only hear them once at the beginning of the message when you call a real disconnected number.

Thanks. Never paid attention. Just added one set of tones to the begging of a short "leave a message at the tone" audio file and recorded it on my land line answering machine. Will be interesting to see how many calls disappear.  If that works, I'll put it on my cell as well.

unbeldi

Many (most?) predictive dialers don't get fooled anymore by the SIT tones and Telezapper gadgets.

The software that detects SIT tones does not analyze the information messages following the SIT tones.  The official Telezapper device, I think, didn't even sent the entire tone sequence, but only the first 914 Hz low frequency tone for a fraction of a second.


By the way, Special Information Tones were introduced in 1981.  Here are the primary technical references for SIT by Bellcore.

- CB 154, Specifications for Special Information Tones (SIT) for Encoding Recorded Announcements, Issue 3, Bellcore, June 1983.
- GR-CORE-145,  Compatibility Information for Interconnection of a Wireless Services Provider and a Local Exchange Carrier Network, Bellcore 1992
- SR-2275, Bellcore Notes on the Network, Bellcore 1997, Chapter 6, 6.21.2.1

Other early references are:
- BSTJ 60 no 7, 1289-1312 (September 1981): Special Information Tone Frequency Detection
- BSTJ 61 no 8, 1841-1862 (October 1982): Using Magnetic Bubble Memories to Provide Recorded Announcements


If you can find a free copy of the first two, please do let me know! (CB 154, GR-CORE-145)


thx1138

Quote from: TelePlay on August 27, 2016, 07:07:05 PM
Thanks. Never paid attention. Just added one set of tones to the begging of a short "leave a message at the tone" audio file and recorded it on my land line answering machine. Will be interesting to see how many calls disappear.  If that works, I'll put it on my cell as well.
I'm not sure the SIT tone is going to accomplish anything. As unbeldi says, the telemarketers have just ignored the Intercept SIT. I guess I'll find out when that annoying caller calls again.

I did find that I received far fewer calls when I first started using my program with just the fax handshake. I call the handshake the mating call of computers. One of the things that it does, as opposed to just a recording, is it hangs up on them after 10 seconds. The modem goes off hook which stops the second and following rings, starts the handshake, and hangs up after ten seconds. So although I still hear the first ring because the caller ID data comes in between the first and second rings, if I don't hear a second ring I know it was a rejected call. Makes me smile every time. If I do hear a second ring I know the call was not denied.

TelePlay

It's been over a week since I added the "disconnected" SIT to my answering machine and I do believe it has cut down on 75-90% of messages.

The robo calls are gone but I did get one or two messages from local numbers. My answering machine is right behind me as I work on this computer and when the phone rings, I always let it go to the machine, the caller is gone before my short message after the SIT ends. So, sort of works, and that's a good thing.

No more messages from the IRS warning me it's my last (latest last) warning that they are coming after me and I was getting one or two of those scam messages a week for the past couple of months. You know the one, right?

thx1138

Quote from: TelePlay on September 04, 2016, 01:45:01 PM
It's been over a week since I added the "disconnected" SIT to my answering machine and I do believe it has cut down on 75-90% of messages.

The robo calls are gone but I did get one or two messages from local numbers. My answering machine is right behind me as I work on this computer and when the phone rings, I always let it go to the machine, the caller is gone before my short message after the SIT ends. So, sort of works, and that's a good thing.

No more messages from the IRS warning me it's my last (latest last) warning that they are coming after me and I was getting one or two of those scam messages a week for the past couple of months. You know the one, right?
Ahhh, the sound of silence. It's good to hear it's working for someone.

I haven't received a call yet from my troublesome caller so I don't know if it's working through the modem. I hear the tones when I set my cell phone number to be blocked but don't yet know if the tones will affect this particular caller. They call seldom but when they do, they call every 10 to 20 minutes for an hour which really ticks me off when I'm trying to work.

Yeah, I've heard the IRS warning scam. I don't get those any more. The fax handshake seemed to get rid of them.

TelePlay

An update on my use of the "disconnected" SIT.

Being the political season, I am getting one robo call every two hours or so. When I am sitting within earshot of my answering machine, I hear the subset ring, the answering machine start with the code followed by a "leave a message at the tone" and the message start tone.

I haven't had one message left on the machine in more than a week, and that was a real person who didn't know what the tone meant.

So, thanks for the tip.

And it makes me smile  ;D every time no message is left.

thx1138

Quote from: TelePlay on October 15, 2016, 01:52:11 PM
An update on my use of the "disconnected" SIT.

Being the political season, I am getting one robo call every two hours or so. When I am sitting within earshot of my answering machine, I hear the subset ring, the answering machine start with the code followed by a "leave a message at the tone" and the message start tone.

I haven't had one message left on the machine in more than a week, and that was a real person who didn't know what the tone meant.

So, thanks for the tip.

And it makes me smile  ;D every time no message is left.
It didn't help me with my troublesome landline robocaller but seems to help with other calls.

I'll have to try it on my cell phone. I haven't done that yet