On iOS, some phone carrier seem to be filtering OTP SMS

[anraiki]

My client has brought to my attention that Firebase SMS is sometimes filtered by some carriers (T-Mobile for this case) which prevents it from auto-filling, auto-logging, or even logging through the auth system.

I have a workaround by creating my own SMS OTP that interfaces with Firebase Custom Auth but it is not perfect.

Is there any way to have Firebase SMS OTP be sent through another deliverer such as Twilio?

Or has anyone else found a way to resolve the issue of carriers filtering the OTP?