It is not just Samsung. It is iphone as well. I have an IPhone X. No audio going from me to the outside guest.
Now I just figured it out for my purposes. Apparently even though the doorbell rings and I get the live camera shot, until I hit the unmute button on the right and the green phone off hook button on the left is 2 way audio accomplished.
I just spent WAY TOO LONG on customer service help to not have them help me resolve this and my husband figured it out right away, while at work. Smh!!!