ComwaVe works decent for me. I took the 3 day test. Cool thing is unlimited incoming calls for free. Unfortunately for me my area is not supported so I had to choose the closest city for the phone number I choose.
It definitely sounds better with a headset and mic plugged in.
I want to pay the 20 bucks for the year, just to have it for when I really need to make a call. They limit you to 250 outgoing minutes a month, but unlimited incoming. You can also pretty much call anywhere in the world. Problem for me is they won't allow a POST box address, or take my physical address. Oh well, i'll have to email them.
Not great, but pretty cool on a fat wifi connection. It's in appworld. Give it a try with your gear.
I concur,Comwave is excellent! Tested it outside the country to call home many times without an issue. Plus you can use it on any other computer not just the PlayBook