| Number | Name | Date | Kind |
|---|---|---|---|
| 3777058 | Stidham et al. | Dec 1973 | |
| 4118790 | Cockett et al. | Oct 1978 | |
| 4252998 | Astegiano et al. | Feb 1981 |
| Number | Date | Country |
|---|---|---|
| 1281168 | Jul 1972 | GBX |
| Entry |
|---|
| "KDX-O International Telephone Switching System" 1972 International Switching Symposium, 6-6-72, Nakazome et al. |
| "Mechanized Combined Line and Recording System" GTE Automatic Electric Technical Journal vol. 13 #5, Jan. 1973, Behnke et al. |