Although the telephone conveys the spoken word with ease, it is illsuited for the written one needed for pagers or communication with the deaf. The telephone keypad contains only ten alternatives (something twelve), far fewer than the 26 alphabetic letters plus space, which means that a single press of a button is ambiguous. The traditional arrangement ABC/DEF/GHI/JKL/MNO/PRS/TUV/WXY omits Q and Z, but these can be understood to be in their normal positions.
Eckler, A. Ross
"Sending Messages by Telephone,"
Word Ways: Vol. 28
, Article 13.
Available at: https://digitalcommons.butler.edu/wordways/vol28/iss4/13