Same exact problem, it's driving me insane. I have been using the HTC Nexus One for a while now, with no serious problems (been great!) -- but recently I have discovered that all my outgoing calls do not transmit my voice to the other party. Sometimes, if I reconnect with them (they call me back, or I call them back) right after, the call is fine, but even after a few tries this is not always the case.
- Covering the noise cancellation microphone does not seem to have a significant effect on whether or not the other party can hear me. Neither during the call or for the entire duration of the call.
- Sometimes switching to speakerphone, pressing mute, and alternating these actions, has an effect. But this is not consistent.
- I have performed a factory reset, but this seems to have only made the problem more common.
- Bluetooth devices seem equally affected by this problem; so using a Bluetooth headset does not get me around this.
- PCM Audio Recorder (an app for Android) also records nothing (silence) during phone calls, but this may be because android does not permit a third-party app to record conversations.
Since I can't actually make any phone calls... my phone is essentially a lesser tablet and it's just frustrating.
I sent HTC support a copy of this message, so... I'll post here if I hear back from them. Please let me know if you guys find any solutions!
Edit: I've also done repeated testing by calling friends and calling myself through Skype.