In the past few months my iphone 7 plus began to echo while I'm in the middle of a phone call. It doesn't happen all the time, but seems to happen once or twice per day. When it happens it usually lasts 15-20 seconds, then goes away. It sounds like an old fashioned broken record, skipping and such. Any one know how to fix this issue? I'm on my phone a lot (for work) so this is a real issue for me. Gracias.