Panasonic’s KX systems were everywhere in small American businesses from the 1990s on.
The myth
People online say Panasonic systems had a built-in melody chip. The KX-TA824 programming manual lists exactly two music-on-hold sources: External (the factory default) and Tone. With nothing plugged into the music port, callers hear silence. The bigger KX-TDA adds an “Internal” source slot, but we found no factory tune documented for it.
The later KX-NS can hold up to eight uploaded WAV files, one active at a time (System Program 711), or use an external source or a tone. We found no factory melody there either.
If you have Panasonic documentation that names a built-in tune, we’ll happily correct this.