# Can someone on a touch-tone phone tell by sound what number you are dialing?

**URL:** https://boards.straightdope.com/t/can-someone-on-a-touch-tone-phone-tell-by-sound-what-number-you-are-dialing/430371
**Category:** Factual Questions
**Created:** [December 17, 2007, 7:32pm UTC](https://boards.straightdope.com/t/can-someone-on-a-touch-tone-phone-tell-by-sound-what-number-you-are-dialing/430371 "2007-12-17T19:32:48Z")
**Posts on this page:** 3
**Page:** 2

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### Author: ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)
#### Post date: [December 18, 2007, 12:59am UTC](https://boards.straightdope.com/t/can-someone-on-a-touch-tone-phone-tell-by-sound-what-number-you-are-dialing/430371/21 "2007-12-18T00:59:19Z")

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[QUOTE=Shamozzle]  
You guys ever heard of [Captain Crunch](http://en.wikipedia.org/wiki/John_Draper)?  
[/QUOTE]

It’s worth noting that the Cap’n was famous for building “blue boxes,” simple circuits that generated the in-band signaling tones for routing long-distance calls. These were not the DTMF tones discussed here. Almost all long-distance switches now use digital out-of-band signaling, making blue-boxes obsolete for wreaking havoc.

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### Author: ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)
#### Post date: [December 18, 2007, 3:17am UTC](https://boards.straightdope.com/t/can-someone-on-a-touch-tone-phone-tell-by-sound-what-number-you-are-dialing/430371/22 "2007-12-18T03:17:55Z")

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As sort-of said above, any genuine Western Electric touchtone phone (like these [http://images.google.com/images?hl=en&q=western+electric+2500&gbv=2](http://images.google.com/images?hl=en&q=western+electric+2500&gbv=2)) will generate the pure tone of a column when 2 buttons in that column are pressed, and ditto for two buttons in a row. Pushing 2 buttons on a diagonal produces silence.

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### Author: ![diggleblop](https://avatars.discourse-cdn.com/v4/letter/d/ac91a4/32.png) [@diggleblop](https://boards.straightdope.com/u/diggleblop)
#### Post date: [December 18, 2007, 7:01pm UTC](https://boards.straightdope.com/t/can-someone-on-a-touch-tone-phone-tell-by-sound-what-number-you-are-dialing/430371/23 "2007-12-18T19:01:59Z")

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My brother has [perfect pitch](http://en.wikipedia.org/wiki/Perfect_pitch) and can do it.

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