There appears to be a common issue affecting a number of Galaxy S8 users, whereby the person on the other end of a voice call cannot hear any sounds coming from the S8 owner. I was also affected by this issue, and nothing seemed to resolve it (although admittedly I was too hesitant to try a factory reset – given others already claimed this did not resolve it for them).
For me, the issue only occurred when I was connected to my home network. Playing around with relevant WiFi related features, I discovered the issue went away when I disabled Wi-Fi calling.
To disable Wi-Fi calling:
- Open the phone app.
- Go to settings (click the icon at the top right).
- Scroll to the bottom of the Call Settings page.
- Disable “Wi-Fi calling”.
- Restart your phone.