My device has sound quality issues on speaker phone I am told it is really difficult to hear me on the other end of the call when on speakerphone
Also the phone rebooted twice when attempting a WhatsApp videocall
Also calls seem to drop out but strangely if you immediately phone the person back the call just seems to reconnect
If you're quick enough the person has not finished their sentence
I found the crackling disappeared after a couple of days use
it was doing it in headphones and speakers but not bluetooth
I came to the conclusion it was possibly because the headphone socket and speakers had never been used before
all good now