i bought this phone cracked screen for about $300...it is iphone 4g..16gb.....It is unlocked with 4.0 version...so I changed the screen and the LCD, but I pelple can't hear me when I call them....on the other hand, i can hear them....also they can't hear me even when i use the headphones or the bluetooth.....however, when i use tengo, they can hear me well.......what is wrong with my phone??? any answer will be appreciated