TELECOM Digest OnLine - Sorted: Re: Touch Tone vs. Rotary -- Desk vs. Wall Sets?

Re: Touch Tone vs. Rotary -- Desk vs. Wall Sets?

Dan Lanciani (
Mon, 28 May 2007 02:03:59 EDT (Curtis R Anderson) wrote:

> From memory, there was a curiosity in the early DTMF cards vintage
> 2500-type phones. The tone generator ICs originally used required more
> than just tying the row and column together from the keypad to generate
> the tone. On the 2554 I had, the Mostek IC required a separate contact
> closure for the row and/or column to either the positive or negative
> terminal.

ICs? In vintage 2500 sets?

Dan Lanciani

[TELECOM Digest Editor's Note: YES! It's true; but technically they
were not _vintage_ 2500 sets. They were 2500 sets which had gone back
to be refurbished for whatever reason; when they came back from the
'refurbishing factory' they had little chips inside them in place of
the traditional guts. They were '2500 sets' in name only, with wee
tiny circuit boards in them; there were not a lot of them, but I had
one when I lived in Chicago. I thought they were all junk; my neighbor
had one also, and when I had my CB radio on, her '2500 set' phone picked
up the CB radio harmonics. They were very light weight, compared to
the older, traditional models. They had no bell and clapper inside,
for incoming calls they sort of made a chirping noise. All junk, IMO.
More accurately, I would say they looked like 2500 sets to people who
knew little or nothing about telephony. PAT]

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