Issue

Some Twilio customers using Event Streams to monitor inbound SMS traffic may notice that messages containing reserved keywords such as HELP, STOP, or INFO do not generate com.twilio.messaging.inbound-message.received events, even though other inbound messages do. This article explains why this occurs, how Twilio’s SMS STOP Filtering feature works, and what to expect for Event Streams delivery.

Symptoms

• Inbound SMS with reserved keywords (e.g., HELP, STOP, INFO) are received by Twilio (visible in Messaging logs).
• No corresponding Event Streams event is delivered to your webhook or sink for these messages.
• No error appears in Twilio Debugger.
• Non-reserved inbound messages (e.g., “Test message”) do generate Event Streams events as expected.

Product

Twilio EventStream 

 

Environment

Twilio Console

Cause

By default, Twilio enables SMS STOP Filtering on all accounts. With this feature enabled:

• Inbound messages containing reserved keywords (HELP, STOP, INFO) are not passed to customer webhooks or Event Streams sinks.
• These messages are redirected to a separate internal account for compliance processing.
• As a result, no com.twilio.messaging.inbound-message.received event is generated for these keywords, and your application will not receive an Event Streams event for them.

This behavior is by design and ensures compliance with industry regulations regarding opt-out and help keywords.

What About Other Inbound Messages?

• Inbound SMS that do not contain reserved keywords (e.g., “Hello”, “Test message”) will generate Event Streams events and be delivered to your configured webhook or sink as expected.

Resolution

1. Confirm the Message Content:
   Check if the missing Event Streams event corresponds to a reserved keyword (HELP, STOP, INFO).
2. Review Account Settings:
   By default, SMS STOP Filtering is enabled. If you require different behavior, contact Twilio Support to discuss your use case.
3. Test with Non-Reserved Messages:
   Send a standard message (not a reserved keyword) to your Twilio number and confirm that the Event Streams event is delivered.
4. Check for Other Issues:
   If you are not receiving Event Streams events for non-reserved messages, further investigation may be required.

Additional Information

If you are not receiving Event Streams events for inbound SMS containing reserved keywords, this is expected behavior due to Twilio’s SMS STOP Filtering. Only non-reserved messages will generate Event Streams events by default. For special requirements, contact Twilio Support.

Below you will find references to useful documents:

• SMS STOP Filtering: Behavior and How to Disable
• Customizing HELP/STOP messages for SMS filtering
• Twilio Event Streams Documentation

Frequently Asked Questions

Can I receive Event Streams events for HELP, STOP, or INFO messages?

Not by default. These messages are filtered for compliance and are not delivered to customer webhooks or Event Streams sinks.

What if I need to process these keywords for my application?

Please reach out to Twilio Support to discuss your requirements. In some cases, SMS STOP Filtering can be adjusted for specific use cases.

Are there any logs or errors for these filtered messages?

No error is generated in Debugger or Event Streams. The filtering is silent and by design.