Hi Jules22, Please check whether you have attached any 3’rd party screen protector. Some of the Samsung-unapproved protector accessories like films, covers, vinyl which attach on the device backside may cover even Camera or Flash, and this causes to block the Air Path inside the device. Due to the blocking of Air Path, the sound is not heard clearly or is broken irregularly, and volume may be also low. Also, make sure that the protective vinyl attached to protect the device during production and distribution is completely removed from the device without blocking the microphone hole.
Hi BIGBILLY204, Is the other person can hear you properly?
Is this issue occurring with just one particular contact?
I suggest you please make sure your device is updated to the latest version and also please try restarting the device and check if the issue got resolved.