My phone mic doesn't work?

Whenever someone calls me and I answer or vice-versa and I start talking their phone doesn't pick up my voice and it seems like I am not talking. I even tried taking a video to see if it was my phone and I yelled "Bob" a bunch of times and when I went to view the video it didn't say anything. This no "troll" by the way. What do you think is wrong with my phone and it's the Alias 2 also.