How do I troubleshoot SMS delivery delays in Amazon SNS?

Short description

SMS delivery might be delayed for the following reasons:

• The recipient's device is experiencing technical issues such as storage limitation and low signal strength.
• The phone number is temporarily out of the coverage area.
• The phone number is in a roaming network.
• There's increased network traffic for a particular carrier.
• The device was turned off when a carrier tried to deliver the message.

Resolution

Follow these troubleshooting steps for your use case.

Troubleshoot single device issues

1. Restart the device so that it's connected to the nearest network base station.
2. Change the SIM slot to check for a device issue.
3. Check the devices message storage, and then delete messages that are no longer needed.
4. Make sure that the device can receive SMS messages from other sources.

Troubleshoot multiple device issues

If delayed SMS delivery affects multiple devices, there might be issues with downstream providers and carriers.

To troubleshoot potential downstream issues, create a support case for Amazon SNS. Provide the following information in your support case:

• The AWS Region that you use to send SMS messages.
• A timestamp of when the issue started.
• Three samples of SMS logs with the message IDs of failed SMS messages to different phone numbers not older than three days.

Note: Mobile carriers might not store SMS information for more than three days.
Important: SMS deliveries from Amazon CloudWatch Logs don't always provide accurate SMS delivery times. In some cases, SMS messages can be delivered before CloudWatch logs are received. The dwellTimeMsUntilDeviceAck value in the delivery logs shows when the carrier accepted the message, but doesn't provide information on delayed SMS messages. For more information, see Viewing CloudWatch metrics and logs for SMS deliveries.

Related information

Monitoring Amazon SNS topics with CloudWatch