Brand new, sealed iPhone 4S, no voice! Help???

I bought an iPhone 4S 16GB black as a gift from manhattan beach in CA, I asked the representative if it works in Lebanon (middle east) she said yes, when i arrived i updated to 5.1.1 and voila, no voice!! at all it works when i use ear-phones!! ideas?!! it is factory unlocked and it was sealed....etc I looked and tried almost everything, mute button, sound control from general.....etc nothing is working