I have found a work round to the problem. The mute button is not working and so the phone thinks mute is switched on. Go into settins, General, Accessability, Assistive Touch, Device and turn off mute on the phone. There will be a little circle you use to access this. You will have to repaeat the process is the phone is swithched off.
Intel Coffee Lake 8th-gen Core processors release date rumours