| Number | Name | Date | Kind |
|---|---|---|---|
| 3647973 | James et al. | Mar 1972 | |
| 3870821 | Steury | Mar 1975 | |
| 4304968 | Klausner et al. | Dec 1981 | |
| 4426555 | Underkoffler | Jan 1984 | |
| 4440977 | Pao et al. | Apr 1984 | |
| 4532378 | Nakayama et al. | Jul 1985 | |
| 4585908 | Smith | Apr 1986 | |
| 4608460 | Carter et al. | Aug 1986 |
| Entry |
|---|
| L. R. Rabiner, "Digital Techniques for Computer Voice Response: Implementations and Applications", IEEE, Apr. 1976, pp. 427-432. |
| Smith et al., "Alphabetic Data Entry Via the Touch-Tone Pad", Human Factors, Apr. 1971, pp. 189-190. |
| "Straight Talk", DECtalk, Inc., pp. 11 and 12, Copyright 1985. |