Q: On phone my voice is blocked but I can hear callers voice clearly

Hello, Mukundk.  

Thank you for visiting Apple Support Communities.  

I understand that callers are unable to hear your voice when using your iPhone 4.  Here are some troubleshooting steps that may help with this issue.  

If your voice is too faint or sounds unclear using iPhone, or iPod touch

Cheers, 

Jason H.