Number | Name | Date | Kind |
---|---|---|---|
3444329 | Krumreich | May 1969 | |
3558831 | Prescott et al. | Jan 1971 | |
3564164 | Prescott | Feb 1971 | |
3657487 | Schwanck et al. | Apr 1972 | |
3898394 | Ward et al. | Aug 1975 | |
4163874 | Lenaerts et al. | Aug 1979 |
Number | Date | Country |
---|---|---|
2536437 | Sep 1976 | DEX |
Entry |
---|
W. Ruffer & W. Wernet; "Hands-Free Calling Goes Residential"; GTE Automatic Electric Journal; Mar. 1977; pp. 275-279. |
I. Yamagami & K. Shirai; "Small Size Telephone Set Design and Construction"; Review of the Electrical Communications Laboratories; vol. 22, No. 3-4; Mar.-Apr. 1974; pp. 221-226. |