I want to use a prepaid SIM card (text and calls only) anonymously. I bought the SIM card offline without providing any address or name.
I am now thinking about using a dumbphone I bought from Amazon and that I previously used my primary, "public" SIM card with (and would do so every once in a while). I only plan on switching the phone on when I want to make phone calls or write a text, probably once every one or two weeks.
Will this compromise my anonymity? If yes, to what degree and who would be able to get to know my identity? Would it be enough to buy a new dumb phone and only use the new prepaid SIM with it?