A MVNO not on T-Mobile that used Passkeys for 2FA and the only way to legitimately port a SIM off the service requires a scheduled in-person interview would be a solid business.

No marketing, all word of mouth from VIPs.

It is NOT possible to secure any SIM-based telephony system against number porting. One layer up from such an MVNO is an aggregator with humans that can be bribed to change the routing for that number.

The solution is to upgrade the telephony network with e2ee and the mobile number secured using ENS and a private key.

3NUM is building a new telco communications stack with privacy and end-to-end encryption, powered by crypto
3num.co

We are working on this @3num 

With @3num a number is first looked up via ENS. If found, it uses e2ee to communicate with that number. If not found it falls back to the legacy insecure network. If both parties use 3NUM everything is e2e secure.

Once players like 𝕏 adopt this, we will stop talking about secure 2FA