Hi, I have a problem with my unlocked european pre 3.

Is very frustrating...Sometimes, when I want to call someone, I can listen him but he can't listen me!
I've tried to switch on/off the silent mode, speaker, to call again,... but the problem persists.
The only way to solve the problem is restarting the phone!!

I hoped with the actualitation 2.2.4 the problem would be solved, but isn't!!

Some idea?