A radio-interference distress call was an old style of communications beacon which was keyed to cause interference in a starship's sensors and navigation systems, attracting attention to an old-style light speed-only radio wave signal. Dating back to a time when subspace communications were largely unreliable or unavailable for distress calls, from the advent of warp until the 23rd century when the time barrier was broken.
In 2254, these signals were somewhat obsolete when just such a call was received by the Federation starship USS Enterprise. Originally mistaken for a gravitational disturbance or object to be deflected in the vessel's path, the signal caused enough disruption in the ship's routine for the proper scanners to be focused on the distress wave, sent from the crashed SS Columbia wreckage on Talos IV eighteen years prior, in 2236. (TOS: "The Cage", "The Menagerie, Part I")