Using gizmo and google voice on my brand new nexus one I had at least 3 or 4 conversations.. one lasting 20 minutes. This is without a headset and through the ear piece. Both incoming and outgoing.. and the 20minute one was driving on I4 60-70mph in Florida. I had a spot where it dropped... and another couple spots where it got a little broken up, but the voice quality using sipdroid 1.3.3 (which was just released) was only very slightly worse than the mytouch 3g i bought to test the 3g quality in my area for ~2 weeks. This could easily be due to my settings on sipdroid, and its mostly just that the voice volume for both hearing and receiving (for the other person) was low. I have since upped the mic and the earpeice gain in the advanced settings and I'll let everyone know how it goes. This again was over 3g, although the one call with wifi sounded about the same.. and without compression as this version does not allow me to enable compression. Edit: Also I forgot to mention background noise is pretty apparent on the phone with sip droid. For instance the other person said it was noisy when i went over a bridge/overpass (was going 60-70mph and this is on 3g) so it seems the noise canceling mic is just disabled with sip droid. Edit2: Also, battery life is clearly worse making a phone call over 3g, which makes sense cause its data. Will test out more. Just to recap: Its *mostly* the SAME as the myTouch3g which i previously owned. Your voice quality over 3g/wifi is not going to be as good as your normal voice calling.. but i'll take it. Also I'll be adding a review of my nexus one that i received today within the next couple of days once I've been using it for a bit. I've been very fortunate as my phone did not have any dust under the screen upon arrival, battery life seems good (I did it the proper way by fully charging my phone while it was off until the green light came on), and no other issues. I'll be able to report more on battery life etc soon.