It was a paper record of every (paid) phone call. This was in the 80s before the switch to digital. The front side had the origin and destination numbers, the back side had the calling card number.
Also--we didn't use a 10-key! Our keypad was 2x5 rather than 3x3, and inverted (low numbers at the top).
I want to know more!
I assumed numbers were entered directly on a 10-key. Were they scantrons as a paper record, as an asynchronous way to enter the data, or?