

Why telephone keypads are arranged the way they are - squeakynick
http://datagenetics.com/blog/august32015/index.html

======
jacobolus
This blog post doesn’t really add anything beyond what the original paper
says, though at least it links to it, though the OCR font replacement in the
version he links isn’t my cup of tea. The original paper is thorough and well
worth reading for anyone interested in designing keyboard-type input devices.

Here’s a link to a scan where the OCR doesn’t clobber the image
[http://mrserge.lv/assets/human-factors-engeneering-
studies-o...](http://mrserge.lv/assets/human-factors-engeneering-studies-of-
the-design-and-use-of-pushbutton-telephone-sets.pdf)

The lowest errors and fastest keying rate were actually with the standard
circular telephone arrangement (most familiar), followed by the two-row five-
column layout, and those were also the test subjects’ preferred layouts. In
the final test between the 3x3+1 grid vs. the 5x2 grid, the vote tally was
12-3 in favor of the 5x2 gris.

I assume the company’s final choice was based on some engineer or manager’s
aesthetic preferences or non-human-factors technical criteria (e.g. it fit
better on a particular phone body design), though I’ve never seen any concrete
explanations of how the final grid layout was chosen. Or in other words, we
still don’t have a solid answer to the question “Why are the numbers on a
telephone keypad arranged the way they are?”

~~~
kd5bjo
I don't know which came first, but it might have been to make manufacturing
easier give the signaling scheme keypad phones used: when you press a key, two
sine waves are generated -- one represents the row and the other the column.
There's two groups of 4 frequencies for 16 possible buttons; some radios have
an extra column with A-D keys for the extra tones.

~~~
DanBC
Some military phones used the extra keys as part of autovon.

[https://en.wikipedia.org/wiki/Autovon](https://en.wikipedia.org/wiki/Autovon)

> The Automatic Voice Network (AUTOVON) was a world-wide American military
> telephone system. The system was built starting in 1963,

------
tgb
My school had us enter our IDs into a keypad to buy lunch, so I did this
everyday. Then, I had to enter it in a computer and got annoyed as the system
wouldn't take it. Turns out the differences was that the lunch keypad was set
up like a phone with 1 on the top while computers were set up like calculators
with 1 on the bottom. It had become muscle memory and I was swapping two
digits because of the change in entry device. Ever since then I've thought the
incompatibility baffling, as well as surprising that it doesn't cause more
problems. I hadn't noticed it at all until then.

------
squeakynick
Why the difference between numeric keypads and phone keypads?

Numeric keypad layouts mimic calculator layouts, which in turn, mimicked the
original ‘adding machines’. The inventors of these early devices did not
perform extensive user based testing (as it often the case in technology;
early adopters end up creating standards that others follow, good or bad).

The whole point of the article is the Bell labs undertook an extensive user
based study to investigate which layouts might be better (Pretty much the
first time this testing had been done on this issue). They tested both
canonical forms of the (3x3)+1 layout and selected what we now know today as
the telephone layout. (If I had to speculate as to why this layout performs
slightly better than the calculator layout, I might suggest that, in the West,
we read left->right and top->bottom and so this is the more natural numbering
scheme).

Had extensive testing been performed by the original adding machine
developers, maybe both devices would use the same layout.

Interestingly, the most creative benefit I’ve heard for keeping the calculator
layout as it is, is because calculators are often used to sum up real world
measurements, and these fall under to purview of Benford’s Law* Because of
this, the keys which are more likely to be used as the leading digits are
closer to the at-rest position of the hand and require less energy to move and
press … yeah … I’m not convinced either, but it sounds good 

* [http://datagenetics.com/blog/march52012/index.html](http://datagenetics.com/blog/march52012/index.html)

~~~
jacobolus
The keys near the rest position of the hand are 4, 5, and 6. The zero key is
not in a particularly convenient spot for the thumb (it should be moved down
and to the left), and the 1, 2, and 3 keys require relocating the
index/middle/ring fingers from their home positions. The delete, space, comma,
period, tab, equals, parentheses, and various operator symbol keys are mostly
also inconveniently located, though the enter and plus keys are fine.

I don’t think the standard calculator numpad layout is defensible on digit or
symbol frequency grounds.

Even if we want to keep the numbers in the standard place for the sake of
familiarity, I would recommend adding some keys and relocating others,
something like
[http://i.imgur.com/BnYqKLW.png](http://i.imgur.com/BnYqKLW.png)

------
TazeTSchnitzel
Here's a fun tidbit. DTMF supports ０１２３４５６７８９＊＃ as you probably know. But it
_also_ supports Ａ, Ｂ, Ｃ and Ｄ - not present on modern phones. These tones were
added for use with remote computers and such, think today's phone menus.

The lack of them means there's a whole DTMF "column" gone. DTMF works on a
grid. When you press a key, the tone for the row and the tone for the column
are played simultaneously:

    
    
      (Hz) 1209  1336  1477  1633
          -------------------------
      697 |  1  |  2  |  3  |  A  |
          -------------------------
      770 |  4  |  5  |  6  |  B  |
          -------------------------
      852 |  7  |  8  |  9  |  C  |
          -------------------------
      941 |  *  |  0  |  #  |  D  |
          -------------------------
    

Given the DTMF grid matches the typical layout on dialing pads, I wonder if
early DTMF phones would wire the pad in the same grid to generate the
corresponding tones?

------
jsnell
There's two things I found surprising. That they tested so many circular
arrangements, and that there was a measurable difference between the two 3x3+1
orientations.

If the author of the post is reading this, the image of the two vertical
columns is wrong. On the site it's essentially two columns, in the paper it's
five rows. That is rows 15 26 37 etc compared to 12 34 56 etc. It makes for a
surprisingly large difference, at least to me. The former looks completely
unusable, the latter seems quite ok :-) So maybe I should not be surprised
that the two 3x3+1 setups didn't perform the same...

~~~
simcop2387
I'd guess that the circular patterns are all because of the norm at the time
being rotary dials.

------
henrikschroder
How curious, I had no idea american dials went from 1 to 0 with 0 the longest
to dial! Where I'm from, they went from 0 to 9, with 0 being the shortest
number to dial, like this:

[http://www.skrotnissen.se/prylshop/common/pic/whitegoods/dsc...](http://www.skrotnissen.se/prylshop/common/pic/whitegoods/dsc06666.jpg)

(This is why the emergency number is 911 in the US, whereas it used to be
90000 where I'm from)

Anecdote number two is that when I was working in Denmark in 2004 or so, I
noticed that all the number pads on credit card readers were calculator-style,
not phone-style, which was a legacy from when Dankort was rolled out in the
early 80's, _just before_ keypad phones surpassed rotary dial phones.

(In 2010 or around there, most retailers switched their card readers to phone-
style layout, so all stores had to have small signs apologizing for it, but
mentioning that the rest of the world had phone-style layout, so let's just
all get in line with the program...)

~~~
henrikschroder
Better images:

[https://en.wikipedia.org/wiki/Ericsson_Dialog](https://en.wikipedia.org/wiki/Ericsson_Dialog)

Swedish original on top, US market models on the bottom.

~~~
bootload
_" The ergonomics of the handle was a focal point in the design. Additionally,
the acoustic, production, and aesthetics aspects needed to be resolved. The
handle was fitted in size according to the dimensions of an average face,
which had been taken as the starting point of the design process."_

Superior ergonomics & one of the reasons I dislike modern smart _cough_ spy-
phones. The audio is shite and software keys are no replacement for actual
tactile feedback. Luckily they (rotary dial 800 series) are still available ~
[http://www.vintagephones.com.au/ccp0-catshow/refurbished-
tel...](http://www.vintagephones.com.au/ccp0-catshow/refurbished-telecom-pmg-
rotary-dial-phones.html)

------
thinkingkong
Kind of ignores how DTMF phones worked. The tones are actually two tones
played simultaneously. Each row and column are separate tones. Laying them out
in a circle could work but its not very practical.

~~~
gruturo
Pretty sure DTMF came way later than pulse dialing - first keypads were just a
change of interface but still pulse dialing.

~~~
analog31
If there was an early time when pushbutton phones used pulse dialing, it must
have been brief. All of the pushbutton phones that I ever saw as a kid were
DTMF. I'm not sure how a pushbutton pulse phone would have worked without
digital electronics. This was at a time when, in the US, the phone company had
a monopoly on phones, all phones were rented, and you actually paid more for
"touch-tone" service.

Later on, the phone regulations were changed, and you could own a phone.
That's when cheap pushbutton phones came out, that had a switch allowing you
to choose between pulse and tone dialing, because you still had to pay more
for touch-tone service and some regions didn't offer it.

The weird thing was, sometimes you had to use both, for instance at my
college, the phone system used pulse dialing, but I had to enter a "calling
card" code using tone dialing in order to call my parents and put the call on
their bill.

~~~
bencoder
I definitely remember (as a child in the UK) that our touch-tone phone had a
pulse option that could be switched on the underside. If you flicked the
switch then instead of a tone you would hear click-click-click-click when you
pressed a number. This would have been in the early to mid-90s, though we were
quite poor so the phone might have been older.

~~~
makomk
It took quite a long time for the UK phone system to be converted to support
tone dialing everywhere so there were still places in the UK where pulse
dialing was required. The last Strowger exchange, where the pulses directly
stepped the switches, was only taken out of service in 1995.

There were phones out there that had a keypad but only supported pulse dialing
too; if I remember correctly, my parents had one when I was a kid.

------
bsagert
I worked as a telephone repairman in the dial era. Impatient diallers would
often "push" the dial back rather than let it unwind naturally. Switch gear in
the central office was sensitive to mis-timed pulses so wrong numbers often
resulted. Also, as mentioned elsewhere, the early keypads sent pulses rather
than DTMF, which made for an annoying clicking sound in one's ear.

------
kbutler
I'm curious about the difference between the calculator and phone layouts.

I expect that the bias to the winning phone design came because of the bias in
phone numbers - that is, because rotary dial phones would dial lower numbers
more quickly, lower numbers were more sought after, and were allocated to
higher population areas. This was both for personal convenience, and because
it tied up the phone lines for less time with the dialing pulses.

I expect that this asymmetry also introduced a bias toward the 1-on-top
dialing pattern that won, though I don't see analysis to that effect. (The
original paper simply stated "that the arrangement frequently found in ten-key
adding machines...was not the best [in its group]...the same geometric
configuration with a different numbering scheme [one on top] was superior in
keying performance... However the performance differences between the two were
small".

Of course, the two arrangements primarily differ in which keys are obscured by
your hand, and the proximity of the 0 key, which shouldn't be commonly used,
so maybe this is just post-hoc reasoning...

------
_paulc
Isn't there a simpler reason - a square design is easier to implement with a
3x3 matrix switch and the number layout ensures that the letters associated
with the digits are in alphabetic order.

------
dghughes
Related to this I recall reading (somewhere) about going from a keypad back to
a rotary dial and how infuriating it is even though there's only a tiny
difference in speed.

We humans get used to the speed as little as it is and having to go back to
the old way and it's only 1/2 or even 1/10 second slower drives us crazy.

~~~
astrobe_
The major difference is that with a keypad you can type at your own pace,
while with a dial you have to 1) wait 2) a variable amount of time for the
rotary to go back in initial position for each figure. Furthermore keypads
allow "muscle memory". I'm not old enough to have used extensively rotary
dials but I think it's very hard to form muscle memory with rotary dials. As
an aside, I don't think the difference in speed the two is "tiny".

~~~
dghughes
Oh no rotary dials you got into a rhythm mostly the sound.

For medium numbers kaching ticka ticka kaching, for the first numbers 1, 2, 3
it was really quick like tick tick tick.

The zero or even 7, 8, 9 seemed to take so long compared to the other numbers.

------
x0054
What I wonder about is why they didn't choose the calculator layout, or,
conversely, why don't calculators use phone dial layout. In both cases speed
and accuracy are very important. So, why the difference.

------
digi_owl
The circular dial pads had me look up a Nokia oddity.

[https://en.wikipedia.org/wiki/Nokia_3600/3650](https://en.wikipedia.org/wiki/Nokia_3600/3650)

Note btw that it ran Series 60, meaning Symbian. Meaning that for all intents
it was a smartphone.

And while not circular, Siemens also had a oddity:

[https://en.wikipedia.org/wiki/Siemens_SX1](https://en.wikipedia.org/wiki/Siemens_SX1)

And yep, that one is also running Symbian with the Series 60 UI (licensed from
Nokia).

------
dazzla
I worked in a call center where people where simultaneously using a phone and
keyboard number pad accurately and not even noticing. Subtle differences
between the two but still interesting.

------
0x0
Did the "calculator" layout yield much worse results than the winning inverted
layout? If so, I'm really curious about the reasons for the difference in
performance.

Should actual calculators adopt the phone layout, too? I've always been
curious why not all devices use the same order (PIN entry pads, phones,
calculators, etc.)

~~~
yodon
While not a complete answer to your question, American Scientist's much more
detailed review of phone keypad design history says the final phone layout
produced "significantly shorter keying times" than other layouts (with the
exception of a layout with two five button horizontal rows that had to be
rejected for other reasons) [1]. It also reports the differences between the
top five contenders were statistically indistinguishable (but it doesn't
record which designs were in those 5) and that the designers were aware of the
calculator layouts (which were actually a lot less consistent at that time
that most people assume today), so if the calculator layout had been in the
top 5 it's likely they would have gone with it.

None of the calculator companies had the budgets or human factors research
experience to do the kind of analysis that Bell Labs did (including some of
the earliest true NUI UX research), so they just picked whatever design made
the most sense to their engineers [2].

[1]
[http://www.americanscientist.org/libraries/documents/2005761...](http://www.americanscientist.org/libraries/documents/20057611634_306.pdf)
[2] [http://www.vcalc.net/Keyboard.htm](http://www.vcalc.net/Keyboard.htm)

Edit: correcting the quote to "significantly shorter" from "much shorter"

------
johnsonjo
There is a numberphile video about at&t's article.
[https://youtu.be/kCSzjExvbTQ](https://youtu.be/kCSzjExvbTQ)

------
mode80
'We still "Hang up" when we want to terminate a call, and this refers to the
action of placing the receiver back onto the hook of a phone ...'

oh my god. I'm old.

~~~
kuschku
Interestingly, in German – where we mostly used phones like [1] originally, we
use the word "Auflegen" (put upon) to mean the end of a call.

Different technology shapes language.

[1]:
[https://upload.wikimedia.org/wikipedia/commons/e/ed/Telefon0...](https://upload.wikimedia.org/wikipedia/commons/e/ed/Telefon04_2.jpg)

------
Nano2rad
Telephone dial is anticlockwise, dialed clockwise.

------
Nano2rad
The final winner three-by-three plus one is the only one suitable for mobile
phone. Perhaps because in mobile phone screen is used as reference; in the
phone keyboard the receiver used as reference. In the calculator and adding
machine are not moved around and the table is used as reference.

~~~
jpatokal
The blog post describes a study published in 1960.

