Cornell's "I'm On Hold" follows some of the industry standards, particularly around frequencies and compression, which is one of the reasons he wrote it with a country-ish melody, wanting something simple but catchy, with only a single instrument and vocals. But in other ways, "I'm On Hold" totally upends the genre by breaking the cardinal rule — that hold music shouldn't call attention to itself.
**If you have an IP based telephone system digital equipment may not be necessary. In this case we will provide you with an audio file in the proper format for your IP system.

For those still using analogue or digital phone systems, voice on ISDN circuits has a bandwidth of around 4000Hz. The audio from an analogue phone is sampled at 8000Hz, and because of the nyquist theorem, must be low-pass filtered to 4000Hz. So any frequencies in the audio beyond 4000Hz are lost. Interestingly, the human ear and mind are good at recognising human speech, so this is considered "toll-quality" voice, i.e. good enough to pay for. This is the reason why certain vocalised letters are difficult or impossible to tell apart on the phone. For example, the differences between B, P, T, C, etc. are almost entirely above 4000Hz.
* * A voice over script must accompany every order. The music is not available alone.