cell phone make screechy noises while on call I'm using Sony Xperia J , Why does my cell phone make screechy noises while on call? sounds like a dial up modem
also , my cellphone is not rooted
There are three reasonable possibilities:


Your phone has a problem, most likely hardware.
Your service provider is having problems.
Your phone is not fully compatible with your service provider.


Possibility #1 is the most likely.

To check for #2, call your service provider and see if they are having issues.  To check for #3, ask your provider if your phone is compatible with their network.