Dean Bubley has some insightful commentary about HSUPA and what it means to VoIP over 3G in his latest posting.
I’ve used HSUPA on my Novatel Data Card via AT&T’s 3G network and clearly see the difference, especially with mobile video conferencing. There’s a major quality advantage with HSUPA over HSDPA as the upload seems to be more consistent and delivers what I’ll call “fatter” bandwidth. Not only is is faster, its more stable and seems to show less jitter or packet loss.