If you’ve ever received a Twilio error code, you’ll know what it means. This code means your message was sent to an unreachable number. A variety of reasons could cause this error, including an out-of-service handset, or a violation of the destination carrier’s guidelines. If you receive this error, it’s important to know what to look for and what you can do to fix the problem.
If the message you sent was flagged as violating carrier rules, Twilio will block it. This may be due to the content of the message or the usage of a URL shortener. In the US, using a URL shortener is against carrier policies. Using the full URL will ensure that the message is delivered without issue.
To fix this error, you can use a number of tools. First, you can use the Request Inspector to look at the entire call’s history. You can also try replaying a request by using the Request Replay feature. This will replay the same request that caused the original error, including the header information.