I still have a working iPhone 4 which I use together with a alarm clock with dock as a expanded alarm clock and I do not have any issues at all. So maybe the t

I still have a working iPhone 4 which I use together with a alarm clock with dock as a expanded alarm clock and I do not have any issues at all. So maybe the trick is when you do not use your old iPhone as daily driver anymore pull out the SIM card and everything seems to be OK (would not recommend to use old iPhones in the wild anyway, due to severe security risks)