A walkie-talkie, or handheld transceiver, is a portable device designed to allow its user to both receive and broadcast content. The earliest iterations of the walkie-talkie were developed during the Second World War (as the Motorola SCR-300) by the Galvin Manufacturing Company, and initially had to be stored in a backpack due to its size, although a smaller model, the AM SCR-536, was able to be carried by hand, albeit at the cost of transmission quality. In the decades since, they have become more and more portable and are now used for a huge variety of purposes involving long-distance communication, such as in the military, police force and various companies, as well as for casual purposes and as children’s toys.
Many walkie-talkies were in use on Isla Nublar, and could be found inside Jurassic Park’s Toyota Land Cruisers, mounted on the dashboards. They were used by the resort’s inspection team during their stay on the island to relay important information between cars and the control room, such as how several Velociraptors had stowed away on the Anne B cargo ship. However, as a tropical storm struck the island, the transmission quality of the radios deterioated massively, and although engineer John Arnold speculated that the problems were caused by the storm, it is possible that Dennis Nedry’s sabotage of several of the park’s computer systems also had a part to play. Walkie-talkies were also used by Drs. Henry Wu and Alan Grant as Wu navigated Grant through the park’s generator shed, and by Robert Muldoon to communicate with John Arnold and Dr. Wu as he tranquilised the park’s Tyrannosaurus and evaded Velociraptors in the wilds of the island.
Source: www.wikipedia.org, Jurassic Park, by Michael Crichton, pages 135-6, 172-4, 288 318, 321, 307 (Fifth reprint)