03. *The same use case mentioned above but both the SIMs are from the same telco with which we are live. So if a user is trying to register via the SIM, not on mobile data, we will send them a failed verification report, correct?

Same scenario as above, we will return FALSE if the user is entering the phone number of the SIM which is not connected to data, and client can fallback to SMS (they should do this if they confirmed that current user has multiple SIM slots on the device, so they can assume it’s Dual SIM device).