Okay - I can hear nothing on the phone. I can make calls, microphone works as folk can hear me and I can hear my own answer phone messages. I can hear nothing on speaker, the handset or a headset. I know that the speaker works as I can play my iPod and listen to answer messages...
I've reset and reloaded the software numerous times. Nothing. I wish I could try reverting to a pre 2.2 version as I think that is the problem.
if you've done all those things and still are experiencing issues, if you are still under warranty, i would contact apple for a replacement (either calling, or if you're close enough, set up an appt at the genius bar).
Yesterday (2/4/09) this happened to me. Same symptoms - people could hear me but I couldn't hear the phone dial or the people on the other end. I did hear the ringer but not the speaker. I only had the phone since Oct. 8. Tried everything on the forum - reset, headset in and out, turned off bluetooth. Finally called Applecare. It was a hardware problem and they replaced the phone. Funny thing - one minute the phone is fine, the next it failed.