Straight Talk Wireless Broken Phone Service Internet

Straight Talk L38C LG Optimus Dynamic phone connects with callers but often around 50% of the time I can hear them but they can't hear me. The microphone is fine I can still talk to my virtual pets and it soemtimes works. I have almost lost a job because of this phone breaking bug

Straighttalk doesn't have a clue how to fix it and it runs the gamut of phone manufacturers Like Samsung, LG and the iPhone. So it must be straight talks network. I use verizon towers and others run on AT&T towers.