Zenith had experimented with subscription *television* since 1931, and had completed a system in 1947. "Phonevision" was trademarked. In 1951, with FCC approval, a limited test involving 300 Chicago families was conducted.
Each day for 90 days, Zenith broadcast a Hollywood motion picture available to any family for $1 (not cheap, a new Buick was $1800 then). The families watched an average of 1.73 movies per week. More than the average, but not enough to justify a commercial venture.
In 1954, a second test of an improved system was made, this time in New York City using WOR facilities to determine the effectiveness in a high broadcast density environment. The over-the-air coding/decoding mechanism worked well and the test was considered a success.
In October of 1954 the first contract was concluded for the use of Phonevision for Australia and New Zealand. I do not know what happened as a result.
The mechanism lingered on until the seventies without any real success. In 1971 a test of a limited number of subscribers was made in Hartford, Connecticut, but again the setup expense was considered to be to high for commercial viability. It took the mass-market penetration of cable to make pay-per-view effective.
The original PhoneVision required a dedicated phone line to each subscriber's house. Later ones used on-the- air signals, but all required a special decoder box.
Two types of billing saw experimental use. The first had a coin-operated box on top of the TV. When the proper amount was deposited, it would retrieve the decoding information over the phone line to unscramble the signal.
Later designs required the user to call a number on the telephone and authorize the charge in exchange for a code. Entering the code into the box unscrambled the picture.
Today Zenith is one of the top manufacturers of cable TV decoders. Few realize it all started back in the '30s.
btw: Zenith began regular colour TV broadcasts in Chicago back in 1940 using a "colour wheel" mechanical method and field sequential transmission. When the American standard NTSC (known as "Never The Same Colour") was adopted in 1953 by the FCC (under tremendous lobbying pressure by RCA), the field sequential colour TV system also became "dead media."