Debugging Common Issues with SMS

There are several ways to troubleshoot an undelivered SMS message.

1. Check your Messaging logs for a record of the SMS request. If you don't see a record of your message at all, the message likely encountered an error in your application or potentially with Twilio's API:

   • You can look at your error logs to see what error was caught, if any.

2. If the SMS isn't in your logs and your application code is generating an error:

   • You can find some sample requests for sending SMS messages in your language of choice here on our documentation. These sample requests can help isolate any syntax issues that may have cropped up in your code.

3. If you can't find the SMS in your logs and you received an error from Twilio:

   • If you received a 4XX response from Twilio's API, Twilio encountered a problem and wasn't able to send the message. You can look up the code you received in this list of errors .

4. If the message is marked Undelivered or Failed in Twilio's logs:

   • In this case, Twilio received a delivery receipt from one of our carriers indicating that the message was not delivered. This can happen for several reasons , including carrier content filtering or the availability of the destination phone.

5. The message is marked Sent or Delivered in the logs but wasn't sent to the device:

   • To further debug, check out the section below for troubleshooting tips when a message doesn't arrive at your device.

Read more in the Troubleshooting Undelivered Twilio SMS Messages support article.

There are several questions you should ask if messages are not reaching your Twilio number:

1. Is your Twilio number SMS-enabled? Does it have a webhook configured?

   • Log in to your Twilio account, navigate to the Phone Numbers section and click on Manage Numbers .

   • Any number that shows the SMS icon can send and receive SMS messages:

     Rate this page:

     12345