The Way Things Work - Season 1 Episode 26 Telecommunications

In the final episode of the series, the Inventor attempts to introduce a telephone network to Mammoth Island after the islanders begin using the dangerous method of flinging coded boulders to Dodo Island in order to communicate. Complications arise when the mammoths begin using the telephone poles as scratching posts, necessitating the use of mobile phones. Topics covered: telephones, exchanges, satellites, signals, mobile phones, fiber-optic systems.