The Fleischers, Dave and Max, invented the rotoscope technique for combining live action film and animation, and this film is one of the earliest uses for this technique (besides their own "Out of the Inkwell" series from the previous year), and gives a lighthearted overview of how the telephone works.
Max Fleischer today is best-known for creating Betty Boop and animating the first Popeye and Superman cartoons, but he also was a pioneer in producing animated films for industry and the military, both of a technical and scientific nature. Inkwell Studios was so gifted and quick in the turnaround that it took Dave Fleischer only a week to familiarize himself with the workings of AT&T well enough to produce That Little Big Fellow. This was not the first film they had made for the Bell System, and it was not to be their last.
Inkwell Studios films for AT&T:
How the Telephone Talks - 1924
That Little Big Fellow - 1927
Now You're Talking - 1927
Finding His Voice - 1929
Producer: Inkwell Studios, Dave and Max Fleischer
Footage courtesy of AT&T Archives and History Center, Warren, NJ