iphone 5 7.1.2, Verizon
I am having this issue since 4 months. I have received multiple devices as replacement as my phone was still under warranty. Nothing seems to solve this.
I was being suggested below , I tried them all
1. Mark calls with ###, once I marked them they came up with an answer there is nothing wrong with the network , change the phone
2. Next phone had same issues, answer was its due to incoming calls from T mobile.
When I showed them even AT&T people heard it, they suggested to change the phone
3. Next phone had same issues, they suggested me not to use bluetooth and talk from an area with full bars (now dots). I receive at least 3 dots if not 4 or 5 at my home.
4. Next phone, they suggested to not restore the back up but setup Iphone as new. I did and only installed 1 app. Still people on other side had screeching sound, this time it was Sprint and T mobile both.
Funny part when I called apple support and verizon for the first time, even they could hear that sound.
No one seems to know why this is happening. I may buy a basic clamshell phone, insert my SIM card in that and use it for a few days to deduce if its device related or carrier. Again I am no expert.