With my new Galaxazy S8+ I'vehad for 3 weeks, when receiving or making a phone call the person on the other end cannot hear me at all unless I put them on speaker phone. Why? Also, voice to text does not work in Samsung mode nor Google.
Welcome to Android Central. It sounds like you may have a defective mic, but that wouldn't work either with the speakerphone. Have you taken the phone to your carrier's store and had them take a look?