connectivity bars turn white when calling

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http://androidforums.com – My phone shows fulls connectivity bars, all green. When I make a call or receive a call, it connects clearly. The connectivity bars turn white. I can hear the other person, but they cannot hear me. The connection is good. I have updated firmware, software, etc. I have started and restarted. I have removed the battery. why do the bars turn white and why can't the person on the other end hear my voice? Thanks (General)