I'm not aware of the details, but I imagine something very similar to EMV payments. The only difference is that you need to register your SIM with the service

I'm not aware of the details, but I imagine something very similar to EMV payments. The only difference is that you need to register your SIM with the service beforehand, using a reasonably secure process. Banks make you use their own MFA before you can enable Mobile ID (and no, it's never over SMS).