Thanks. On your advice, I just tried it with some old SanDisk ear buds -- it does work. Surprisingly, it was the best result on a phone call of any headset I have tried yet. That's pretty sad.
I will be able to test the Etymotic ETY•COM Headset tomorrow and that should give me another good comparison.
At the moment, I'm only concerned with phone call quality. I'm testing mostly VoIP (with Sipdroid), but some cellular calls too. For music listening, I wouldn't use the Etymotic, obviously (it uses only one ear piece).
Making phone calls with the V-Moda Vibe II is a bit weird because they ear buds fit so well in my ears that they block out most external sound -- they even block out my own voice, so talking sounds very weird.