How do I troubleshoot SMS delivery delays in Amazon SNS?

Last updated: 2022-08-18

I get delivery delays of mobile text messaging (SMS) to destination numbers in Amazon Simple Notification Service (Amazon SNS).

Short description

SMS delivery could be delayed for the following reasons:

  • 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 phone was turned off when a carrier tried delivering the message.


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 if the device can receive SMS messages from other sources.

Troubleshoot multiple device issues

If delayed SMS delivery is affecting multiple devices, there could 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 you're using 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 numbers not older than three days

Note: 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 received the Delivery Report (DLR), but doesn't provide information on delayed SMS messages.

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