Problem when placing the call

[nofear232]

I've just got the Motorola RAZR XT910 a few days ago. I used the phone normally without SIM card inserted. However, yesterday (31/12/2011), I put my SIM card on and just found the problem when calling to somebody or receiving a call.

I can hear the voice spoken to me ,but he can't hear any voice from me. The only thing he can hear is the vibrating sound when I pushed the soft-key button (UI Interactions). I can temporarily plug the headset in (Earphone+Microphone) ;however, I don't want this problem to occur with me forever. Should I look into settings to configure something?? I really do need your helps. Thank you.

Thanks in Advance
nofear232

Additional information: I can use Google Voice Search without headset. (Speak directly to the phone). Thank you