1-800-key-padd

September 21, 2006 9:07 AM

Can anyone tell me why telephone keypads are "upside down" relative to calculator/numeric keypads?

e.g: telephone keypad arranged like so

1 2 3
4 5 6
7 8 9
* 0 #

(i've observed that most ATM/banking machines also orient their keypads in this way -- perhaps to maintain the familiarity of a telephone)

calculator/adding machine/numeric keypads are arranged like so:

7 8 9
5 6 7
1 2 3
0 .

what's the reasoning (if any)?

I ask because when looking at a computer screen for a telephone number, i often "touch type" the number I'm trying to dial on the phone, and of course, it's upside down from the computer keyboard I work with all the time.

posted by I, Credulous to technology (9 comments total)

straight dope says:

"Basically, calculator keypad design evolved from cash registers, while telephone keypad design evolved from the rotary dial. Tradition has kept them that way ever since."

More here.
posted by triv at 9:20 AM on September 21, 2006

I understood it as an artifact that was created to slow users, some of whom were already 10-key familiar, down to a speed that the early phone circuitry could handle. Phones have long since been able to handle faster entry but it now remains as an established standard.
posted by geekyguy at 9:20 AM on September 21, 2006

geekyguy - wasn't that argument more about typewriters?
posted by triv at 9:23 AM on September 21, 2006

If there were phones that had them the 'right way' - would people buy them? I would. What about mobile phones?

What if this was something that could be set in user preferences where the buttons are dynamic based on what the user wants?

Would it still make sense to keep the same letters associated with the same numbers? How would that affect SMS?

Would this be something that would be as hard to do as say switching to metric?
posted by Monkey0nCrack at 9:33 AM on September 21, 2006

Would it still make sense to keep the same letters associated with the same numbers?

Yes! For example, all those companies that invested in 0800-GROCERIES or whatever wouldn't want to have to change the number you dial!

How would that affect SMS?

It wouldn't if the same numbers are still the same letter. They'd just be at a different place on the keyboard.
posted by easternblot at 10:38 AM on September 21, 2006

AT&T says, "Extensive human factors tests determined the position of the buttons to limit errors and increase dialing speed even further. "

The Wikipedia article on DTMF goes into a little more detail on this.

I'm inclined to believe them, since the high cost of switching systems meant minimizing the time devoted to each customer's call was a big deal. Making the keypad faster to use for most people and decreasing the number of errors* accomplished that.

At the time (I don't know how it works now) central office equipment could only deal with a certain number of off-hook lines at a time. On top of that switching the call was another very costly operation. The phone company did everything they could to minimize the expensive-to-buy-and-maintain equipment required for satisfactory service.

Since you can't erase a bad button push on a touch tone phone, a dialing error means the customer has to hang up and start over. This means the line was tied up unnecessarily during the first (bad) dial and also potentially doubles that call's dialing overhead.
posted by Opposite George at 10:47 AM on September 21, 2006

doh! clearly, my pride got in the way of actually previewing everything in my post, hence the middle row of the "calculator" layout is completely buggered.

thanks to triv for his answer and link -- I shoulda googled before ask.mefi, I guess. :)

And to MonkeyOnCrack: Me Too! I would totally buy an "upside down" phone...and perhaps one day they'll create a phone (mobile or otherwise. Are you listening Nokia!?) with LCDs in the keycaps to let the user choose which layout they prefer...would benefit the SMS crowd, too, as the characters assigned to each key could be edited/organized to user preference. I could probably do better at all kinds of phone-related entry (names, addresses, etc.) if the keypad would switch to QWERTY when in "letter mode"
posted by I, Credulous at 10:56 AM on September 21, 2006

This is a cultural thing and it does vary - I've seen "upside down" telephone keypads in Denmark, Sweden and Norway. So you can get them, just be aware the plugs and sockets are a slightly different size, so you would have to do some rewiring.

Possible reasons: early IBM keyboards for european countries didnt include a numeric keypad at all, using the extra keys for diacritics etc.

Also those countries had a historically low takeup of fixed-line telephones which could have made a difference, but I doubt it's something the designers put any concious thought into.
posted by Lanark at 12:32 PM on September 21, 2006

I seem to recall something about American Telephone & Telegraph having some kind of propriety on the specific arrangement of numeric keys, and the "flipped" arrangement being settled upon by IBM (or some other adding machine company) to satisfy the lawyers of the time.

It could be just my brain going crazy...
posted by Aquaman at 6:13 PM on September 21, 2006