Hello trinidad98,
Thanks for coming to the Apple Support Communities for help with your iPhone's mic during calls, and we'd be happy to look into this with you.
Does this continue if you remove any screen protectors, films, or cases from your iPhone and clear any debris from the openings? Does this continue during FaceTime calls as well?
Please try the steps in the following link, and let us know the results:
If the microphones on your iPhone aren't working
We hope this information is useful. Kind regards.