The Messaging Error – SMS trigger is a powerful automation tool that enables you to initiate workflows in response to failed SMS delivery attempts. When an SMS message cannot be delivered, the system generates a specific error code indicating the reason for failure, ranging from invalid numbers to carrier issues or blocked content.

Implementing the Messaging Error Trigger #

To add this trigger to your workflows, go to the Automation > Workflows tab. From there, either choose an existing workflow or create a new one.

Next, click the Add New Trigger button and search and select “Messaging Error – SMS” as the trigger event.

Assign a clear and descriptive name to the trigger to ensure easy identification within your workflow.

Add filters to refine the trigger by specifying particular error codes. This lets you target and respond only to relevant messaging failures, ensuring the workflow is activated under the appropriate conditions.

Supported Error Codes #

This feature supports the following error codes, which can be selectively included or excluded based on your requirements:

• 21211: The “To” number is invalid or improperly formatted.
• 21408: Messaging not permitted to the specified region.
• 21606: The “From” number is invalid or improperly formatted.
• 21610: The recipient has opted out by replying STOP.
• 21614: The “To” number is not a valid mobile number.
• 21635: The “To” number is a landline and cannot receive SMS.
• 21661: The “From” number is not capable of sending SMS.
• 30002: The sub-account has been suspended and cannot send messages.
• 30003: Unreachable / out of service number.
• 30004: Do not want SMS / DND enabled.
• 30005: User inactive / number does not exist.
• 30006: Landline / incapable of receiving SMS.
• 30007: Carrier violation.
• 30008: An unknown error occurred during message delivery.
• 30011: MMS is not supported by the recipient’s device or region.
• 30023: Daily A2P messaging limit reached in the U.S.
• 30032: Toll-Free number not verified.
• 30033: The A2P campaign has been suspended or deleted.
• 30034: A2P registration pending on number.
• 30037: Outbound messaging has been disabled for this account.

Once you are satisfied with your configurations, save the trigger to your workflow.

This provides improved message deliverability and contact quality, minimizes wasted sends to unreachable or non-compliant numbers, enhances control over how your system handles delivery failures, and reduces reliance on support teams for error resolution. By leveraging this trigger, you can automatically respond to undelivered messages with tailored workflows, such as notifying internal teams, retrying the message, or escalating the issue for further review.

Frequently Asked Questions #

What does the Messaging Error trigger do? #

It starts a workflow when an SMS fails to deliver, using the error code generated by the system to identify the cause.

Where do I add this trigger? #

Go to Automation > Workflows, open or create a workflow, click Add New Trigger, and select Messaging Error – SMS.

Can I respond to only certain errors? #

Yes. Add filters specifying particular error codes so the workflow activates only for the failures you care about.

What does error code 21610 mean? #

It indicates the recipient has opted out by replying STOP, so messages can no longer be delivered to that number.

What actions can follow this trigger? #

You can notify internal teams, retry the message, or escalate the issue for further review.

Why use this trigger? #

It improves deliverability and contact quality, reduces wasted sends to unreachable numbers, and lets you manage messaging errors proactively without relying on support teams.