My car Radio and CD player suddenly stops and phone is displayed in the station

What is your question?

This issue started in April and has continued to present. It lasts for 30 seconds then the Radio or CD start to play as soon as the phone message disappears for about 3-4 minutes later it does it again, All day everyday since April. We have disconnected the battery for 30 minutes and reconnected it and still does the same thing. Our car looks like it could have Onstar but we don't subscribe to it. We have had the car for 3.5 years and want it fixed but are not sure how to do that.