larry@uunet.uu.net (Larry Lippman) (09/27/89)
In article <telecom-v09i0406m01@vector.dallas.tx.us> carroll1!dtroup@uunet.uu. net (Dave Troup) writes: > Does anyone know what the recording alert tones are? You know-those > dee-doo-DOO, "The number you have reached..." What are the frequencies > to them. Ive NEVER been able to find out what those are. These tones are called SIT (Special Information Tones). Their purpose is to permit an automatic Call Disposition Analyzer (CDA) to differentiate between a human voice and a recorded announcement, and to categorize the type of recorded announcement. A Call Disposition Analyzer is an automatic device, today totally computer-controlled, which automatically dials test calls over certain test subscriber lines, tandem trunks and intertoll trunks for the purpose of evaluating the connectivity and grade of service of all or a portion of the DDD network. A CDA may access a local subscriber line and outpulse using DP or DTMF, or in the case of tandem or intertoll trunks outpulse using MF. A CDA may be programmed to dial a milliwatt test line (102-type from tandem or intertoll) or a transmission/noise measurement ATMS responder test line (105-type from tandem or intertoll). The results of test calls are logged and categorized. The SIT tones facilitate categorizing a call failure which results in a recording. I don't know the SIT frequencies, either, except that they are not far from 600 Hz. The two CDA's which I have seen (Northeast Electronics and WECO) did not in fact have any frequency discrimination circuitry; they merely looked for three sequential tones occurring in less than 3 seconds using a bandpass filter centered around 600 Hz. Actually, I believe that AT&T had some more grandiose plans for the SIT tones which in fact were not implemented. Last I knew - which is actually some years ago - the same department at AT&T which assigned the verbal tandem and intertoll announcement failure codes for recordings said stay tuned for SIT assignments. I stayed tuned for a while, but never heard anything. :-) <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
macy@hal.uucp (09/28/89)
In article <telecom-v09i0412m01@vector.dallas.tx.us> kitty!larry@uunet.uu.net (Larry Lippman) writes: >X-TELECOM-Digest: volume 9, issue 412, message 1 of 9 >In article <telecom-v09i0406m01@vector.dallas.tx.us> carroll1!dtroup@uunet.uu. >net (Dave Troup) writes: >> Does anyone know what the recording alert tones are? You know-those >> dee-doo-DOO, "The number you have reached..." What are the frequencies >> to them. Ive NEVER been able to find out what those are. > These tones are called SIT (Special Information Tones). Their >purpose is to permit an automatic Call Disposition Analyzer (CDA) to >differentiate between a human voice and a recorded announcement, and >to categorize the type of recorded announcement. SIT Tone information follows: Special Infomation Tones (SIT) are a series of three tones at the beginning of intercepted call. These tones are used by call processing equipment to automatically identify the type of intercept the call has reached. SIT Tone type and usages Period Frequency Designation SSL LLL IC - Intercept - Vacant No. or AIS or etc. LLL LLL NC - No Circuit (Inter-LATA carrier) LSL HLL VC - Vacant Code SLL HLL RO - Reorder Announcement (Inter-LATA Carrier) LSS LHL #1 - Add'l Reserved Code SLL LHL RO - Reorder Announcement SSL HHL #2 - Add'l Reserved Code LLL LLL NC - No Circuit, Emergency or Trunk Blockage Where: Period-Duration: S=Short 274 msec L=Long 380 msec Frequency: L=Low 913.8 hz 1370.6 hz 1776.7 hz H=High 985.2 hz 1428.5 hz This information taken from a central office recorder/announcer installation manual ca. 1983. I believe SIT's are specified by Bellcore and/orr CCITT. I have heard SIT's used on international calls to several countries. Macy Hallock fmsystm!macy@NCoast.ORG F M Systems, Inc. hal!ncoast!fmsystm!macy 150 Highland Dr. uunet!hal.cwru.edu!ncoast!fmsystm!macy Medina, OH 44256 Voice: 216-723-3000 X251 Disclaimer: My advice is worth what you paid for it. Alt.disclaimer: Your milage may vary. Biz.disclaimer: My opinions are my own. What do I know?