Why can't i use Apad for voice call?!

I'm having a weird experience with my Apad, i got two unit apad, 1 unit preloaded with original android firmware 1.5 which has microphone disabled, and the second unit has been upgraded to Hybrid Rom 6 beta and the microphone is working fine, the problem is when i try to make a voice call using fring from the second apad to call the first apad, my wife is handling the first apad with microphone disabled she can hear my voice clearly but i cannot hear her voice of course, and then i try to upgrade the firmware in the first apad from original to Hybrid Rom 6 beta, well since they are using the same firmware i have now 2 unit apad with microphone function enabled right? yes, and then i try to make another voice call using fring and something irritating happened, both device don't have speaker sound enabled during the calling progress, i cannot hear my wife voice and vice versa, with SIP on fring i can make a phone call to my wife nokia phone and her blackberry phone and she can also hear my voice but once again when she speak i heard nothing NO SOUND, what is wrong?? can somebody help me to solve this? you can add my fring id "eroticid" for testing purpose, thanks in advanced