Bad sound quality during calls
Hi, I' recently experience bad sound quality during calls. The problem seems to occur when calling from one Iphone to another. The sound is distorted and loud and can't pick up what the other person is saying. It's not a volume issue, it's loud enough, but a quality-issue. If I switch to Facebook Messenger-call, the sound is excellent. This is also the case when I receive calls from a landline.
I've followed a lot of trouble-shooters, also from Apple, by turning off Wifi-Calling, 4G, VoLTE Off and turned Phone Noise Cancellation Off, but nothing seems to take. I also did a factory reset. I really don't think it's a microphone/speaker issue, as other audio works fine.
Any suggestions? The Iphone X is excellent, and I don't want to replace it.
iPhone X