[Lex Computer & Tech Group/LCTG] How to use a telephone, from 1954

[Ken Pogran]

The analog in-band tone signaling system was developed way back in the 
late 1930s, when the equipment needed to generate, and receive, the 
signaling tones was all vacuum-tube based and found only in telephone 
central offices. (Not only was there the 2600Hz on-hook/off-hook 
supervision signaling, but also the two-out-of-five code 
multi-frequency—MF—signaling of called numbers.)

Tone signaling systems were deployed with long-distance ("toll") 
switching systems, starting (IIRC) just before WW II. "Long Distance" 
operator consoles had keypads enabling operators to signal the distant 
phone number you wanted (obviously way before Direct Distance Dialing in 
the late '50s).

Once it became really easy to build battery-powered transistorized 
circuitry to generate the requisite tones, the whole system became 
vulnerable to hacking in the '60s and '70s.

Ken Pogran

Steve Isenberg via LCTG wrote on 4/9/25 11:35 PM:
> I found that I could call an 800 number, whistle the frequency, and 
> hear the tandem drop; I didn’t need the Captain crunch whistle.
>
> On Wed, Apr 9, 2025 at 10:29 AM Adam Broun via LCTG 
> <lctg at lists.toku.us <mailto:lctg at lists.toku.us>> wrote:
>
>     Did anyone here ever use the infamous Cap'n Crunch whistle?
>
>     On Wed, Apr 9, 2025 at 10:23 AM Donald Cooke via LCTG
>     <lctg at lists.toku.us <mailto:lctg at lists.toku.us>> wrote:
>
>         They came around to Hancock School to teach us kids. Must have
>         been my 5th grade or so. Our number changed from
>         Lexington-9-0524 to Volunteer-2-5010. I think we also got to
>         walk down to the switch station on Waltham Street to see the
>         switching mechanism.
>
>         Later on I learned that I could dial a number by just pressing
>         the hangup switch rapidly.....
>
>         Don Cooke, Site 523, 603.219.9259
>
>
>         On Wed, Apr 9, 2025 at 5:43 AM John Rudy via LCTG
>         <lctg at lists.toku.us <mailto:lctg at lists.toku.us>> wrote:
>
>             Bing Videos
>             <https://www.bing.com/videos/riverview/relatedvideo?q=how+to+use+a+dial+phone+1954&mid=7F1DA87AF463381268157F1DA87AF46338126815&FORM=VIRE>
>
>             This is pretty amazing
>
>             John Rudy
>

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