I'm having a weird issue.  I have two 7921's i'm trying to troubleshoot a problem for.  So let's say phone one is: 4000 and second phone is 4001.

When phone 4000 calls 4001, 4001 when rings twice and the user picks up.  This is where the problem beings, no one can hear each other.  It is dead silence.  The phones hang up and 4000 tries calling 4001 again, same thing happens.  Phone 4001 does see that 4000 is calling via caller ID, but when 4001 picks up, they can't hear each other.  It doesn't happen all the time though.  I have phones on A radio.  We have adequate coverage in the area too.  Any thoughts as to why this might be happening?  This isn't happening to just these two phones but may happen with other 7921's in the area.

Thanks