How easy is it to fake a SIM card to receive SMS?

Question

mobile connection

How easy is it to fake a SIM card to receive SMS?
It is clear that Mr. authorities or representatives of the mobile operator themselves can do this, but is it easy for others?
I ask in terms of whether it is worth using SMS confirmation to access important assets?
Or Google Authenticator is still safer.
PS: hacking, loss of the phone itself, etc., please do not take into account.

Answer 1

To fake a SIM card, you need to know the KI and IMSI codes of your SIM card. It is almost impossible to recognize them. Therefore, to your direct question, the answer is "it is almost impossible."
But SMS interception is possible in ways other than sim card cloning, which are related to tricks with SS7 networks (although this is also not entirely for "ordinary citizens", but given the general level of corruption, it is possible). The defense against this is to make it as difficult as possible for the process of establishing a connection between your identity and the number used. That is, the use of your regular number is excluded.

Answer 2

SMS is unambiguously used, but the number does not "shine" anywhere
+ all possible additional security and protection measures