You often use other SIM cards and a proxy phone

Since the IMSI always appears together with the IMEI in the traffic data of your network provider, you should also change your phone when you change your SIM card. As you can imagine, it is time-consuming and expensive to change your phone from time to time. You would have to constantly set up your apps again and spend a lot of money on a new phone. To keep costs down, you can work with proxy phones. And this is how it works: You have a more expensive device for your regular use on which all your apps are installed. There is no SIM card in this phone. It is therefore invisible to the mobile network. You get Internet access via an inexpensive second device with a SIM card inserted. This phone does not need much power. However, it can provide you with a Wi-Fi hotspot and therefore Internet. You can also use it to make normal phone calls if you want. This phone can be replaced quickly with the SIM card inserted. The only disadvantage is that you always have two smartphones with you.