Walkie-talkies can be traced back to World War II, when backpack-mounted Motorola SCR-300s were used by the U.S. Army Signal Corps, but the walkie-talkies we think of today were actually called Handie-Talkies during the war. The SCR-536 was the first modern handheld walkie-talkie, but it had limited range and was rather bulbous. While not the first two-way FM handheld radio, the HT 220 was significantly more "portable" than its predecessor, owing in part to its integrated circuits.