The TOUCH-TONE® Telephone--Transmission of Digital Information ®
Johan Söderberg, R. Campbell, F. Bates · IRE Transactions on Communications Systems · 1967
A discussion of the Bell System TOUCH-TONE®dialing system when it is alternatively used in data applications is presented. The particular aspects of this service and the hardware involved which lend themselves to alternate data uses are discussed in detail. Among the points covered are coding, the keyboard, error possibilities, and the technical aspects of the receiving data set.