iPhone12Pro Max outgoing audio randomly muted

6 day old phone. On several outgoing calls today, RANDOMLY, the recipient can’t hear me from the beginning of the call. I’m not muting by accident. I’ve tried taking off the case but no difference. But in between these calls, I’ve successfully gotten through. Also, people can call me - no problem. FYI - the outgoing calls have been both local and out of state. Thanks!