My HTC Trophy (Windows 7) phone just picked up the following anomally:
If I call someone - I cannot hear the phone ring, cannot hear them answer and they cannot hear me. If I turn on speaker phone we can hear each other. If i use headphone jack or bluetooth we can hear each other.
I checked the internal speaker by playing music and podcasts - works well.
I checked the microphone by using a recording app - microphone worked well.
I restarted the phone - powered completely off and back on.
I pulled the battery and restarted the phone.
I havent set it back to factory settings because I'm hoping these symptoms will give someone an idea that they can pass along to me.