SNS Phone carrier has blocked this message

Question

We are having issues sending messages for one time passwords from a toll free number already registered and configured for transactional messages, in past days it was working fine, but since yesterday we are getting this error log for all messages:

```
 {
        "Timestamp": "2022-11-28 19:53:04.136",
        "Status": "FAILURE",
        "Message ID": "ba38a5b9-abb8-50b4-97aa-fe46b875a656",
        "Destination phone number": "+1******",
        "Provider response": "Phone carrier has blocked this message",
        "Message type": "Transactional"
    },
    {
        "Timestamp": "2022-11-28 19:49:10.814",
        "Status": "FAILURE",
        "Message ID": "400cbe0f-1e8c-5d15-a24d-e5f00c6fe40c",
        "Destination phone number": "+1******",
        "Provider response": "Phone carrier has blocked this message",
        "Message type": "Transactional"
    },
    {
        "Timestamp": "2022-11-28 19:49:04.603",
        "Status": "FAILURE",
        "Message ID": "3f471359-3ce4-5bf8-b974-48a62e072b29",
        "Destination phone number": "+1******",
        "Provider response": "Phone carrier has blocked this message",
        "Message type": "Transactional"
    }
```

Answer

US mobile carriers have recently changed their regulations and require all toll-free numbers (TFNs) to complete a registration process with a regulatory body. Several other countries have followed suit. As a part of that registration, you specify the content your messages will contain to the carrier along with the use-case. It's possible your messages no longer match what was submitted, or your number was reported as spam.

To view the status of your toll-free number, access the Pinpoint console and view Phone Numbers under the SMS and Voice section. It will display the status of that toll-free number.

For more information on how to comply with carrier restrictions of toll-free numbers, see [AWS' documentation](https://docs.aws.amazon.com/sns/latest/dg/channels-sns-sms-tfn-register.html).

Answer

Hello Juan Castaneda,

When an SMS message is published to AWS SNS, the message is forwarded to downstream Providers. The downstream Providers, in turn, forward the message to mobile phone carriers.

That is, the flow for SMS messages is as follows:
Amazon SNS -> downstream Providers -> Mobile Phone carriers -> Mobile Endpoint
Mobile carrier is responsible for getting the message to the endpoint.

Issues in downstream Providers and carriers can sometimes be the reason for the failures in SMS notifications. As the complete architecture is not under AWS control, you need to let AWS know about issues so AWS can escalate it with the downstream carriers and work with them till the issue is fixed. You can submit you [case here](https://docs.aws.amazon.com/awssupport/latest/user/case-management.html).

With that said, there are also a couple of other reason why SMS delivery can fail, few of them are:
* Blocked as spam by phone carrier
* Destination is excluded
* Invalid phone number
* Message body is invalid
* Phone carrier has blocked this message
* Phone carrier is currently unreachable/unavailable
* Phone has blocked SMS
* Phone is blocked listed
* Phone is currently unreachable/unavailable
* Phone number is opted out
* This delivery would exceed max price
* Unknown error attempting to reach phone

For more information please read this [blog post](https://aws.amazon.com/premiumsupport/knowledge-center/sns-unknown-error-phone-sms/).
Also please check out the [SMS best practices](https://docs.aws.amazon.com/sns/latest/dg/channels-sms-best-practices.html).

Answer

Same problem here. 
Since 4 days, all SMS for MFA code sent to France are in "fail" status because of "Blocked as spam by phone carrier" reason.

All my users are blocked and can't login into my application.

I can't open a support case because it's a technical issue and we have to pay just to submit a case!

SNS Phone carrier has blocked this message

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