The Zenith Phonevision system became the first home pay-per-view system to be tested in the United States. Developed in 1951, it used telephone lines to take and receive orders, as well as to descramble a television broadcast signal. The field tests conducted for Phonevision lasted for 90 days and were tested in Chicago, Illinois. The system used IBM punch cards to descramble a signal broadcast during the broadcast station's "off-time". Both systems showed promise, but the Federal Communications Commission denied them the permits to operate.