Radionics was an early form of wireless communication based on modulation of low-frequency electromagnetic radiation, the radio band of the electromagnetic spectrum. Unlike later communications systems, radionics transmissions were limited to the speed of light, resulting in substantial delays when used over interplanetary distances. As a result, radionics was supplanted by more advanced subspace and holocomm systems, and the technology was largely forgotten.
However, since law enforcement agencies rarely if ever monitored radionics transmissions, the technology found some use among smugglers. Lando Calrissian had a radionics transmitter and receiver on his yacht Lady Luck, along with an accompanying portable unit. In 18 ABY, he gave Tendra Risant the portable unit shortly before being forced off her homeworld of Sacorria, intending to return later to communicate in secret. This unit played an important role in the Corellian Crisis, as Tendra noticed a massive military buildup in Saccoria and fled in the Gentleman Caller to the Corellian system to warn Lando. While system-wide jamming rendered modern communications systems useless, radionics systems were unaffected, and Tendra was able to pass on vital information about the Sacorrian Triad's fleet.