use a burner sim like: https://www.twilio.com/wireless/pricing. presumably twillio is harder to social engineer than [big telecom]
Also, keep in mind that an adversary can grab your text messages even without any social engineering skills; they just need to rent a cell tower somewhere in the world and advertise your number as roaming there [2]
As you implied, it is probably safer to use a different number than your main one for SMS-based 2FA (the much-maligned security through obscurity), but before you go out and buy a second phone plan, consider issues such as whether you will be able to receive SMS messages while traveling internationally.
[1] https://support.twilio.com/hc/en-us/articles/223181668-Can-T...