TELECOM Digest OnLine - Sorted: Re: NY Times Reporter Seeks Info About History of the SIT Tone

Re: NY Times Reporter Seeks Info About History of the SIT Tone
29 Aug 2006 14:26:52 -0700

davidk wrote:

> special information tone.

What is this tone? Is this the three tones when you reach a bad number?

> My name is David Kocieniewski, I'm a New York Times reporter
> researching a story about the development and history of the special
> information tone.

The following website has some information:

The situation of "intercept" for when someone dials a non-working
number was recognized at the very beginning of dial service. In panel
switching, calls were routed to an intercept operator who checked
into. The dialed number may not be assigned at all or been

Dial PBX switchboards had separate appearances for intercept calls,
distinct from dial 0 attendant calls.

The Bell System gradually automated this function. The first was a
recording to ask the customer to dial again, but remain on the line
for an operator. This would handle most errors in dialing and allow
the intercept operator to serve changed numbers.

Then computers enabled storage of vocal digits in a natural way to
automate the whole process so the entire process was automated.

Actually, they attempted to automate recorded and playback voice many
years ago using a drum with motion picture sound film (using the sound
track). Each track had a digit on it and the proper tracks would be
selected. One use was for dial-to-manual exchanges to announce the
incoming number, instead of using a lighted panel. Another was to
return routing information. I don't think either application got very
far with the technology available at the time.

We had a Bell recording announcement machine, controlled by a keyset,
and it was large. I believe the recording was held on some sort of
drum that rotated. Considering the heavy playback and low maintainence,
plain recording tape couldn't be used as it would soon wear out.

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