SIM port attack turns out to be
a very-simple-money even for teens. IMO, to prevent this carrier providers should at least temporally charge for the swap (say $1000) and refund it after SIM original owner confirmed it. If not then that swap should be canceled and money not be returned.
For sure that is already have been thinking or tried by some telecommunication providers, but they should also think some of the parts where their customers will easy to swap their sim cards in a legit way, that's why this Sim Port Attack is started to spread.
For me, the best way to do is actual sim swapping per customers, like the customer is allowed to go in some branch or office of their telco, but this is kinda not comfortable for the side of the customer.