When I talk to someone on the phone, a Sony Xperia 10 II with SFOS 5.1.0.11, with the speaker on, the person I talk to hear echoes and a generally bad sound, that disappears as soon as I switch the speaker off. Sometimes the sound is good at first, but suddenly during the call the sound in the other end becomes bad.
If I remember correctly, on Sony Xperia 10 II with speaker on people get echo, and I don’t remember if it was only sailfish problem or Sony android too.
Some times that this happens when I am on call from speaker on or headphones, and the receiver gets an echo, I terminate the call, restart audio system from utilities and call again.