| All Patents of Type: communication apparatus |
Patents 1 -
5
of 5
      |
| Number | Date | Patentee | Title | Type |
| 218,707 | Aug. 19, 1879 | M.J. Maxwell, C.H. Billings | Improvement in mechanical telephones | communication apparatus |
| 230,698 | Aug. 03, 1880 | R. Eickemeyer | Speaking-telephone | communication apparatus |
| 243,214 | Jun. 21, 1881 | I.W. Colburn, H.J. Colburn | Acoustic telephone | communication apparatus |
| 249,233 | Nov. 08, 1881 | R. Eickemeyer | Speaking-telephone | communication apparatus |
| 2,292,387 | Aug. 11, 1942 | H.K. Markey, G. Antheil | Secret communication system | communication apparatus |
