For the cost of that integration, the bank could also just implement 2FA correctly. U2F, TOTP, even proprietary crap like Symantec VIP are all inherently resist

For the cost of that integration, the bank could also just implement 2FA correctly. U2F, TOTP, even proprietary crap like Symantec VIP are all inherently resistant to SIM swaps because they keep a secret key on the actual device; PSTN routing doesn't matter.