Firebase Auth stopped sending SMS to one of the carriers

[Vlad Lisovyk]

Hello! Our app users started complaining that they were not receiving OTP passwords and are unable to login. We figured that all the complaints are from users of the same carrier –  carrier says everything is working fine on their part. 

There is no firebase support we can talk to and no 'carrier status dashboard' of any sorts –  and we are at a loss. Anyone has advice how to proceed? It's happened before with Firebase Auth for us in the previous year.