https://www.scientificamerican.com/article/first-picturephone-requires-an-enormous-pocket/

“By this month it should be possible for a New Yorker, a Chicagoan or a Washingtonian to communicate with someone in one of the other cities by televised telephoning. The device to use is called a Picturephone and is described by the American Telephone and Telegraph Company, which developed it, as ‘the first dialable visual telephone system with an acceptable picture that has been brought within the range of economic feasibility.’ A desktop unit includes a camera and a screen that is 4 3/8 inches wide and 5 3/4 inches high. AT&T says it cannot hope to provide the service to homes or offices at present, one reason being that the transmission of a picture requires a bandwidth that would accommodate 125 voice-only telephones.”

—Scientific American, July 1964