I hate those iphones even though I have 2 of them. Long story! I miss the good ole days when I had a landline with an answering machine. Watching news on a tiny screen with all those ads is just not my "cup of tea."
I have had those phone echos on cell phones and computer phone services on and off for the last twenty years. I believe it is caused when two or more different cell phone or internet providers relay messages to each other. Like when you get switched from one communications tower to another.