the person on the other end cant hear me.

[Chana1]

i JUST bought my treo 700p on ebay and got it Friday.It is flashed to Cricket so I got it activated Monday. when i tried to make my 1st call, i could hear the other person perfectly but they couldn't hear me. i've tried everything. thank God I have a warranty but the guy I bought it from gave me a 7day warranty hisself and he pretty much wont help. says it has to be a setting and to keep trying. im getting frustrated and I've had 2 ppl from palm tech support and my friend who is a computer programmer help and they cant figure it out. PLEASE HELP!!!