| Number | Date | Country | Kind |
|---|---|---|---|
| 57-162917 | Sep 1982 | JPX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4196316 | McEowen et al. | Apr 1980 | |
| 4203011 | Coviello | May 1980 | |
| 4291199 | Densmore et al. | Sep 1981 | |
| 4453040 | Wolf et al. | Jun 1984 | |
| 4491693 | Sano et al. | Jan 1985 | |
| 4517409 | Nagasaki | May 1985 | |
| 4520235 | Morikawa et al. | May 1985 |
| Number | Date | Country |
|---|---|---|
| 0043896 | Apr 1981 | JPX |
| 0050853 | Mar 1983 | JPX |
| Entry |
|---|
| Ikawa et al., "A Large Scale TDM Electronic Key Telephone System", Intelcon 79 Exposition Proceedings, Dallas, TX 2-26-79. |
| Kopec et al., World-Wide Communications Journal, "Electronic Business Telephone", vol. 18, No. 2, Mar. 1980, pp. 34-40. |