Other people can't hear me while calling...?

[haseebbutt10]

Idk what's the problem but when I call other people using SIM, they say that they can't hear me while other apps which involve sound work fine, even the voice recorder... And when I call using yahoo messenger, it still works fine...
What's the problem? Please help!
I'm running iOS 4.2.1 on iPhone 4.

 

[Maziar]

Are you sure you don't mute the phone when you're on a call ? (or it accidentally gets muted during a call)

 

[haseebbutt10]

Yeah, damn sure... Every thing is fine except calling... No mute nothing else...

 

[Maziar]

There could be a problem with proximity sensor.Update to iOS 4.3.If it didn't help,then bring it to an apple store.

 

[haseebbutt10]

I am software unlocked... Can it be problem with unlock? Or it would be hardware problem?