A walkie-talkie (more formally known as a hanheld transceiver) is a hand-held, portable, two-way radio transceiver. Originally developed for the Canadian government during the Second World War by Canadian Donald L. Hings, similar designs were created for other armed forces, and after the war, walkie-talkies spread to public safety and eventually commercial and jobsite work after the war. Major characteristics include a half-duplex channel (only one radio transmits at a time, though any number can listen) and a push-to-talk switch that starts transmission. Typical walkie-talkies resemble a telephone handset, possibly slightly larger but still a single unit, with an antenna sticking out of the top. Where a phone's earpiece is only loud enough to be heard by the user, a walkie-talkie's built-in speaker can be heard by the user and those in his immediate vicinity. Hand-held transceivers may be used to communicate between each other, or to vehicle-mounted or base stations.