Hi, Nickarata!
Congratulations on your new iPhone! I rely on my own iPhone for communication every day, so I know it's important that you are heard loud and clear. I'm happy to help provide some troubleshooting in regard to the fact that other people are having trouble hearing you on calls.
Give the following article a review, following the steps under the "Get help" section to troubleshoot any microphone issues you may be experiencing.
Get help with the microphones on your iPhone, iPad, and iPod touch
Enjoy your new iPhone!