I've read every forum post I could find. I've tried the recommendations found on 3CX site, YouTube, etc. The 3CX-provided onhold.wav sounds great on internal and external calls put on hold. Every single song I've tweaked to conform to the 8000 Hz, 16-bit, Mono, PCM, WAV format sounds like complete crap, but only on external calls. I can get the volume right, but it devolves quickly into what can only be described as a wind tunnel with a little music in the background. I've limited the volume, adjusted for any peaking, adjusted the EQ to kill the highs and lows, tried different sample rates, etc. Again, it sounds fine on internal calls put on hold, but does the wind tunnel thing on external calls put on hold. My last thought was maybe the Patton SN4312 is doing something weird to the audio, but the default MOH song sounds fine. Has anyone else experienced this and found a fix? I'm running 3CX v12 SP6 on Windows 7 Pro.