If you play a CD for a friend over the telephonewill the friend hear high-quality music?

Telephones systems are designed for speech clarity rather than quality. Typically, the audio bandwidth is 3.5KHz to 5KHz instead of the bandwidth for a CD at 16KHz.

Audio compression and multiplexing is used to carry numerous calls on a single line and these techniques also add to the overall distortion of the signal.

For speech, the low quality is of no importance but for music, there will be a noticeable loss of quality compared to the original,