The long-winded explanation, for those who are interested in how this actually works and why the problem exists: GM uses 128 sound banks, so can never have more than 128 tones ("instruments" if you will) available at the same time. GS extends this, by assigning multiple tones to each of the 128 sound banks, and so it picks a tone using both the usual GM sound bank call and another call for whichever "sub-bank" has to be picked (incidentally, Yamaha's XG uses a similar system to expand sound banks, but its calls are not compatible with GS). The advantage is obvious: you can have a virtually unlimited number of tones (well, technically in the order of 16,000) available to your MIDI composition without having to load different sound sets every time a non-standard instrument is called for. Any MIDI composed on a GS device without using the sub-banks will sound perfectly fine if played back on a GM device. But if it does use the GS-specific sub-banks, it won't. What happens with WOX specifically is that sound bank #125, which in GM is "telephone ring", has sub-bank #2 for "door creak". If you play on a GS device (namely, any Sound Canvas, or any actual GS emulator like VSC), the game calls bank 125 then sub-bank 2, and the door creak plays. If you play the game on a GM device that isn't GS-compatible (such as Windoze wavetable synth), the game calls bank 125... but when it calls sub-bank 2 the MIDI device doesn't recognize the call and skips it, and therefore ends up playing the regular (sub-bank "zero") tone in bank 125, hence the telephone sound.