eli5: Why hasn’t the audio quality of “on hold” music improved in decades?

Question

eli5: Why hasn’t the audio quality of “on hold” music improved in decades?

In: 934

Answer 1

Since 1972 telephones have adhered to a standard that converts sound into digital signals 8000 samples every second or 8000 Hertz (Hz). A tone with a frequency of 200 Hz collects 40 samples each cycle; a tone of 2000 Hz collects only 4 samples within a cycle. The higher frequency that a sound has, the fewer samples per cycle are collected. With fewer samples per cycle it is harder to reproduce the sound accurately when played back at the other end.