Telephone Keypad Design
Read an interesting and insightful article on how and why the telephone keypad was designed the way it is today. Surprisingly its simple, these guys at Bell Labs actually did create multiple versions prototypes and tested with people. The outcome was to be seen in the phones coming further.
The answers to these questions can be found in a fascinating piece of research performed by AT&T in 1960. I strongly encourage you, if you have time, to read their entire publication on the subject. A summary of this work was published in the July 1960 edition of the Bell Systems Technical Journal.
The article was entitled: Human Factors Engineering Studies of the Design and Use of Pushbutton Telephone Sets. You can download a copy of the article here [PDF].
Visit below link to read detailed article.