[donutty]

I used to maintain a MOH system as part of the small PABX at my old work, 6 years ago. This was all digital and ran from a Windows server in conjunction with dedicated PABX hardware.

This suffered from the same problem even though everything was up to spec and I was told it was due to the compression / bandwidth used over the lines. It was understandably even worse when listening to it on a mobile.

Remember, phone lines were designed to transmit voice with a limited range of frequencies, not music. But still, I wonder why they don't 'optimise' MOH tracks to be low-bandwidth friendly. The ones we used were paid for royalty-free tracks specially for telephone use (I still have a copy somewhere!!) so I am surprised they did not make them more fit for purpose.