The Glossoresonator    (April Fool's Day - 1963)

In the week before April 1st, the New York Telephone company announced that it planned to use a new transistorized device called a "Glossoresonator" to intercept prank calls to the Bronx zoo. It noted that on the last April 1, 929 prank calls had been made to the zoo. However, it declined to explain exactly how the glossoresonator worked.

But when April 1st arrived, the company admitted that no such device existed. Nor had its announcement done anything to deter pranksters from calling the zoo. 755 hoax calls were intercepted by operators.