Q: How to disable flash messages.

Block the sender: Block calls and block or filter messages on your iPhone, iPad, or iPod touch - Apple Support

Does the message show up in the Messages app?

OT - redirection

Kilgore-Trout

Can you look into this if you have a chance?

Wallet shows up twice in location services

Class 0 flash SMS are the same type of message that government agencies use to send out public safety alerts and such things.  Your carrier, as far as I understand things now, is correct.  They have no way to block class 0 SMS messages.  They will also bypass your Do NOt DIsturb settings as well.  Once a spammer using these things has your number, I don't know of any way to stop them.  There are numerous phone and carrier forums with all sorts of posts about increasing class 0 SMS spam.

Spammers use jailbroken iPhones or Android phones as those have apps for spamming with "Flash" SMS.

hyunjoongie wrote:

 

My phone isn't even jailbreak   it's an untouched, original one, updated. I bought it straight from Apple.com.

It's really frustrating, it's just people spamming about loans. And since there's no way to track them, I guess most people just dismiss the messages. I just don't have patience for spam, sadly. Wish we could at least track them down.

Michael meant the sender has a jailbroken phone, not you.

Yes, thank you Meg. I was referring to those doing the spamming, not those receiving them.  There is no such thing as a Flash SMS app for native iOS devices, but there are for those who hack their iPhones or use Android devices, so they can send unblockable and untraceable Flash Spam messages.  The recipient is simply stuck with getting them.

Isn't this a Flash SMS app?

https://itunes.apple.com/ca/app/flash-sms-class-0/id723491224?mt=8

You're right, I had not heard of that one.  At least they do not allow it to be used anonymously as they force you to register your phone number and it is displayed in every Flash SMS.  The apps for hacked devices and Android do allow for truly anonymous Flash SMS.

I'll also mention that most USA carriers do not permit Flash or Class 0 SMS messages over their networks (unless generated by themselves as some service alert to their customers).  Some carriers either block the message, or they strip the Class 0 setting from them and deliver them as regular SMS texts to your inbox. In the USA, government alerts are sent over a system known as CMAS, which does use carriers existing SMS system and bandwidth for distribution to peoples handsets, but CMAS is a distinct system and service from normal SMS messages so cannot be used anonymously by non-authorized users to spam people.

I've never gotten a Flash SMS in the USA.  I've only gotten them when I've been traveling somewhere outside of the USA.  I see only a single supposedly Flash SMS app in the US App Store, and the reviews indicate it actually doesn't work as advertised, which I'd be surprised if it did.