Help phone call not working if in normal mode topic

I'm using eXistenz Ultimate 3.00. I cannot make phone calls normally. When i call, the call goes through but i cant hear the recipient nor can they hear me. However, when i turn it into speaker mode, i can hear them fine. I suspect its something to do with one of the settings as when i reset my phone and reinstalled the rom, it worked. But once i fiddled with the settings something went wrong. I don't know which setting is causing the problem or even if the settings are the problem. Please help