I've just had a fascinating and pleasing experience. I had a 15-minute video chat on ooVoo while riding on a bus through the Swiss countryside! First the summary - the quality was good, in fact on my end it was generally excellent, with a few minor pauses as the cellular modem changed towers or technology. The call was never dropped, in spite of those pauses. For those who want to investigate the details, I was on a bus from Solothurn to Herzogenbuchsee.
Now the details. I have a Sierra Wireless AirCard, which I have written about previously, which I use on the Swisscom cellular network. Swisscom has always done a good job in providing high quality cellular service, and they obviously are still doing so. I checked the speed after the call (on speakeasy.net/speedtest), and it was a stunning 835kbps down and 800kbps up! Now, I know that HSPA can theoretically go up to 1.8 Mbps, but I have never seen anything like these speeds before. The last time I checked it, a couple of months ago, I got around 256k each way, so Swisscom is obviously improving their service.
I used ooVoo 18.104.22.168, the latest version, and I was really impressed with the quality of the audio and video, and the fact that it did a good job of keeping up through the cellular tower changes - it was buffering the data and then played it back at high speed when the connection came up again, which probably made me look and sound like Alvin the Chipmunk on speed, but I still find that better than just tossing the data, or even worse just dropping the connection. Another thing I noticed was that even though the connection quality was obviously varying, ooVoo wasn't spending a lot of time, and causing a lot of distraction, by continually trying to adjust the video frame rate and/or resolution.
Of course, I was using my Fujitsu Lifebook S6510, still running Windows XP (SP3), with the built-in Logitech camera, and a Logitech Premium Notebook headset, connected to the built-in audio jacks (not USB).
It's SO nice when it all comes together and works well!