@alzhao Thank you very much for your replies.
As for the first part of the answer, I understand you, the traffic is wrapped in a VPN.
As for the second question. When I insert a SIM card into my phone (that is, an application with a closed code that contains hidden functionality), then I get an operator menu. What this program does is known only to the operator. This can be the transmission of the serial number of the device, data on the country of activation, information about the firmware, the language used, as well as the base station identifier, which can be used to determine the approximate location of the user of the device, for example, Simjacker, etc.
So I was wondering how to avoid this. Or by changing IMEI , MAC address and using VPN am I protected ? If something like a SIM card isolation sandbox so as not to violate my privacy?
I would like to combine the topics as there is also a lot of useful information and your important answers for those who will search. What hardware identifiers can ISP get when I plug in USB 4g modem into Mudi - #4 by alzhao