Disable flash messages (class 0 SMS)

Question: How do I disable flash SMS from inside the phone? (without requesting the carrier network)

Following is how a flash SMS looks like (in any iPhone). After receiving it, the screen turns on, and stays on unusually long. The message appears on top of any other application, and then freezes the phone. I cannot access home screen, lock screen, or multi-task view, or notification window, or even action center. I cannot even turn the flash light in case of an emergency.

The only way to start using the phone is to click the "Dismiss" button, after which, the message automatically deletes itself (and optionally sends a receipt back to the sender).

There is no way to mute/block the person who is sending these messages. There is no way to respond to the person and request them to stop, and there is no way to report this message as spam. Except for the screenshots, there is no evidence that the sender ever sent a message. Fortunately it is not used by many people, maybe because it is not popular right now, but it will be used heavily by spammers in the near future.

I requested the carrier (Airtel) to disable flash SMS, I also followed the sim-applications method that I found on the internet to disable such messages. But flash messages still appear just like before. Clearly we cannot rely on the carrier to disable it. I also tried with the JIO carrier, with the same results!

As such, we need a way to block such intrusive messages from the phone. Or atleast, the message should appear like a regular message, so that we can mute it in messages app, or atleast share it to spam reporting app (new features in iOS 12 allows sharing any message to spam reporting app of the user's choice).

PS: I have been getting flash messages from a company, but I decided not to share their screenshot. Instead, I sent myself a test flash message. For this, I created a new account in a site called msg91, they immediately gave me free 1000 SMS. Within seconds I was able to send flash SMS to anyone. I sent it to a oneplus 6 phone, the message appeared differently. It was less intrusive, the phone was perfectly usable without dismissing the message. There was also an option to save the message, and on clicking that, the flash message converted into a regular message, revealing sender's name. From there, the phone gave an option to block the sender. It is shocking that a budget phone gave a convenient solution to this problem. There are many android application that allow you to send a flash message too.