Hi @b2a.admn
Welcome back to the Auth0 Community!
Thank you for posting your question. Unfortunately, it’s not possible to connect to the 2factor.in SMS gateway in a plug-and-play fashion. The custom SMS gateway is strict, and to connect it to service like mentioned 2factor.in you would need to add an additional proxy layer that would transfer the request to the expected by the SMS gateway provider form. While setting up the middle layer make sure to follow our guide → Set Up Custom SMS Gateway for Passwordless Connections and adjust the proxy accordingly to the request from Auth0.
Thanks
Dawid