692:
530:
511:), to abuse the telephone system and place telephone calls for free, among exploiting other capabilities. SS5 was abused by sending a "seize" signal to simulate and pose as a telephone switching system from a subscriber telephone line. This enabled the perpetrator to control the remote switch that had no means for distinguishing the signaling from that of another legitimate switch.
482:
in traditional
International Switching Centres. Each digit took 55 ms with a 55 ms Inter-digital pause (IDP) and the sequence was sent 'en-bloc' to ensure that Echo Suppressors would not switch out the forward path as the links tended often to be satellite channels. The first digit was a keying
494:
rather than continuous SF tone was used to seize the line at the beginning of a call over that trunk and clear it at the end of the call - long after the valuable register had sent 15 or KF and dissociated from the call. This Line signalling element was 2VF to introduce the possibility of more
105:
to represent decimal numbers (telephone numbers), and the last frequency in combination with one of the others represented the beginning or end of a sequence of digits. These frequencies were combined to encode the following signals:
54:, meaning they used the same channel as the media that they controlled. SS5 was designed for inter-continental traffic for which many transmission paths were long terrestrial, often
495:
meanings and tone-off idle in order that hundreds of channels in transmission media would not be transmitting standing tones simultaneously.
663:
593:
602:
55:
47:
715:
668:
483:
Prefix (a KP) to indicate
Terminal or Transit working and the last digit was the digit 15 or Keying Finish (KF).
643:
468:
code 15, the keying finish (KF or End-of-keying) code instructing the register not to wait for any more digits
59:
424:
code 13, the keying prefix (KP1) where the following digits do not contain a country code (Terminal working)
678:
515:
29:
543:
28:(MF) telephone signaling system that was in use from the 1970s for International Direct Distance Dialing (
586:
446:
code 14, the keying prefix (KP2) where the following digits do contain a country code (Transit working)
102:
479:
696:
535:
51:
579:
638:
66:
connected at their end points. SS5 was specifically designed to work within those links.
63:
25:
487:
709:
648:
44:
because it was used for the first IDDD connections between Europe and North
America.
633:
623:
402:
code 12, or a prefix to reach an individual international operator in the country
571:
628:
508:
70:
658:
562:
525:
613:
653:
618:
504:
380:
code 11, or a prefix to reach any international operator in the country
491:
490:
a 2 frequency (2VF) code using compelled sequences of 2400 Hz and
77:
as
Regional System R1, it used six signaling frequencies: 700 Hz (
74:
503:
The deficiencies of SS5 are widely known as the root cause for "
575:
507:
fraud" that enabled phone phreaks, such as
Captain Crunch (
514:
This fraud was a factor in the widespread adoption of
478:
frequency code was used to pass digits forward between
73:multi-frequency (MF) signaling system known by
101:). The first five frequencies were used in a
62:links. Trunks using satellite links also had
587:
8:
565:- Specifications of Signalling System No. 5
594:
580:
572:
108:
555:
32:). Internationally it became known as
50:in use at the time were designed for
7:
14:
690:
563:ITU-T Recommendation Q.140-Q.180
528:
603:Signaling (telecommunications)
1:
518:(SS7) in replacement of SS5.
732:
687:
669:Multi-frequency signaling
664:Dual-tone multi-frequency
609:
117:
114:
111:
40:. It was also nicknamed
644:Special information tone
679:Signalling System No. 7
516:Signalling System No. 7
674:Signaling System No. 5
544:Signaling System No. 6
18:Signaling System No. 5
697:Telephones portal
103:two-out-of-five code
97:) and 1700 Hz (
58:, and geostationary
716:Telephony signals
703:
702:
536:Telephones portal
486:In addition, for
472:
471:
93:), 1500 Hz (
89:), 1300 Hz (
85:), 1100 Hz (
52:in-band signaling
48:Signaling systems
723:
695:
694:
693:
596:
589:
582:
573:
566:
560:
538:
533:
532:
531:
109:
81:), 900 Hz (
64:echo suppressors
731:
730:
726:
725:
724:
722:
721:
720:
706:
705:
704:
699:
691:
689:
683:
639:Disconnect tone
605:
600:
570:
569:
561:
557:
552:
534:
529:
527:
524:
501:
499:Abuse and fraud
56:submarine cable
26:multi-frequency
12:
11:
5:
729:
727:
719:
718:
708:
707:
701:
700:
688:
685:
684:
682:
681:
676:
671:
666:
661:
656:
651:
646:
641:
636:
631:
626:
621:
616:
610:
607:
606:
601:
599:
598:
591:
584:
576:
568:
567:
554:
553:
551:
548:
547:
546:
540:
539:
523:
520:
500:
497:
488:line signaling
470:
469:
466:
463:
460:
457:
455:
453:
451:
448:
447:
444:
441:
438:
436:
433:
431:
429:
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425:
422:
419:
416:
414:
412:
409:
407:
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403:
400:
397:
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385:
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370:
368:
366:
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353:
351:
348:
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338:
337:
334:
331:
329:
326:
324:
321:
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316:
315:
312:
309:
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300:
297:
294:
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285:
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280:
278:
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272:
271:
268:
265:
263:
261:
258:
255:
253:
250:
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246:
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236:
234:
231:
228:
227:
224:
221:
219:
217:
214:
212:
210:
206:
205:
202:
199:
197:
195:
193:
190:
187:
184:
183:
180:
177:
175:
173:
171:
168:
166:
162:
161:
158:
155:
153:
151:
149:
147:
144:
140:
139:
136:
133:
130:
127:
124:
120:
119:
116:
113:
112:Frequency pair
13:
10:
9:
6:
4:
3:
2:
728:
717:
714:
713:
711:
698:
686:
680:
677:
675:
672:
670:
667:
665:
662:
660:
657:
655:
652:
650:
649:Off-hook tone
647:
645:
642:
640:
637:
635:
632:
630:
627:
625:
622:
620:
617:
615:
612:
611:
608:
604:
597:
592:
590:
585:
583:
578:
577:
574:
564:
559:
556:
549:
545:
542:
541:
537:
526:
521:
519:
517:
512:
510:
506:
498:
496:
493:
489:
484:
481:
477:
467:
464:
461:
458:
456:
454:
452:
450:
449:
445:
442:
439:
437:
434:
432:
430:
428:
427:
423:
420:
417:
415:
413:
410:
408:
406:
405:
401:
398:
395:
393:
391:
389:
386:
384:
383:
379:
376:
373:
371:
369:
367:
365:
362:
361:
357:
354:
352:
349:
346:
344:
342:
340:
339:
335:
332:
330:
327:
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320:
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317:
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310:
308:
305:
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301:
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296:
295:
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288:
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283:
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274:
273:
269:
266:
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259:
256:
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240:
237:
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232:
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229:
225:
222:
220:
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215:
213:
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208:
207:
203:
200:
198:
196:
194:
191:
188:
186:
185:
181:
178:
176:
174:
172:
169:
167:
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159:
156:
154:
152:
150:
148:
145:
142:
141:
137:
134:
131:
128:
125:
122:
121:
110:
107:
104:
100:
96:
92:
88:
84:
80:
76:
72:
69:Based on the
67:
65:
61:
57:
53:
49:
45:
43:
42:Atlantic Code
39:
35:
31:
27:
23:
19:
673:
634:Reorder tone
624:Ringing tone
558:
513:
502:
485:
475:
473:
98:
94:
90:
86:
82:
78:
68:
46:
41:
37:
33:
21:
17:
15:
629:Busy signal
509:John Draper
71:Bell System
550:References
476:2 out of 6
614:Dial tone
480:Registers
60:satellite
710:Category
654:Zip tone
619:Ringtone
522:See also
505:Blue box
358:digit 0
336:digit 9
314:digit 8
292:digit 7
270:digit 6
248:digit 5
226:digit 4
204:digit 3
182:digit 2
160:digit 1
659:2600 Hz
492:2600 Hz
118:Signal
24:) is a
34:CCITT5
75:CCITT
474:The
115:Code
30:IDDD
16:The
38:CC5
36:or
22:SS5
712::
465:15
443:14
421:13
399:12
377:11
138:F
595:e
588:t
581:v
462:X
459:X
440:X
435:X
418:X
411:X
396:X
387:X
374:X
363:X
355:0
350:X
347:X
333:9
328:X
323:X
311:8
306:X
299:X
289:7
284:X
275:X
267:6
260:X
257:X
245:5
238:X
233:X
223:4
216:X
209:X
201:3
192:X
189:X
179:2
170:X
165:X
157:1
146:X
143:X
135:E
132:D
129:C
126:B
123:A
99:F
95:E
91:D
87:C
83:B
79:A
20:(
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