I’m referring to tracfones or similar prepaid devices which you can buy in the US for very cheap. In other countries if you apply yourself just a little bit you can get the same result. Greece has SIM card registration yet you can buy pre registered ones off the street in Athens. Latvia, Lithuania, Netherlands, Estonia, UK, and other countries have no SIM card registration at all and roaming works good across the EU. And you only need the number once to sign up.