> When Touch Tone dialing was introduced, the Bell System came out with
> newly designed desk and wall telephone sets to accomodate the
> The desk set (dial 500, TT 1500/2500) became fatter and higher to
> accomodate the tone pad. However, the wall set (dial 554, TT
> 1554/2554) became slimmer.
> So, I was wondering why the desk set became bigger while the wall set
> became smaller to accomodate Touch Tone? Anybody know?
My Telecom Pioneer aunt gave me a vintage gold colored 2554 set I used
on the lines around here many moons ago when I was in college. I took it
all apart and reassembled it.
What I noticed compared to a gold colored 554 set was that the network
on the (mostly ITT Telecom/Kellogg which I had) 2554 was reduced to a PC
card with quick disconnect male terminals soldered onto the board. The
(mostly Stromberg-Carlson which I looked at) 554's network used that big
box type used on the 500 sets.
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. I am thinking it was some kind of debounce circuitry to keep
the switch from misreading the dialed number. That required extra
mechanisms in the keypad which made those extra contacts, rather than
these days to use something as simple as cheapie single contact
pushbuttons in the keypad. All of that made the tone dial mechanism
thicker than a dial rotor. (Don't get me started on those Nortel dial
rotors which sounded like agitating a box of rocks every time the dial
That newer network combined with the 2554's single gong ringer probably
helped keep its size down. I haven't looked at a new-build Cortelco 2554
to see if the network largely remained the same.
> P.S. While we're on the subject, would anyone know what percentage of
> lines are still served by exclusively dial equipment? I don't think
> they charge a premium for TT anymore. Also, many people have some old
> rotary sets still in service (like me) even if their primary sets are
As late as 2002, I know that Alltel New York (now Windstream) around
Jamestown charged $1.25 or so extra a month to support tone dialing
for residential service. Around 1995 or so, Verizon supplied support
for pulse and tone for customers around Buffalo and continues to do so
today. Good thing, because there are more than a fair number of folks
around here who still have their WE 500 and 554 rotary dial sets
grandfathered from then-New York Telephone.
Curtis R. Anderson,
Co-creator of "Gleepy the Hen", still "In Heaven there is no beer /
That's why we drink it here ..." http://www.gleepy.net/
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