What is max number of retry attempts for Twilio sms callback?

Question

Twilio has provision for configuring callback URL while sending SMS, which is notified of events relating to changes in the delivery state of SMS.

What happens if my application misses one of these callback events? Say for example when my server is down and the callback request encounters a 502 or 500 response.

Does Twilio retry the callback?

If yes, how many attempts are made before abandoning the event notification?

Answer 1

Hope this thread isn't SUPER dead...

I set out to solve this problem myself by making twiliq.com. Disclosure: I'm the dude that made this thing.

You set it as your backup URL endpoint and it'll replay the message as often as you configure until your server recovers.

Answer 2

Twilio developer evangelist here.

Twilio webhooks (for SMS or phone calls) do not make retry attempts to the same URL if your application fails to respond with a 200 response.

However, you can supply a fallback URL that Twilio will request with the same parameters if your primary URL fails. We recommend that this fallback URL is not part of the same application so that if your main application is down, you can recover and continue the conversation, save the errors for later or return an error message to your user.

There is more detail on how best to use fallback URLs on the Twilio site.

Answer 3

Since an answer was posted for this Twilio has added support for retry attempts on webhooks. By default it will retry once on TCP connect or TLS handshake failures, but the type of failures it retries for can be adjusted and the number of retries can be set anywhere between and including 0 and 5.

Documentation can be found here: https://www.twilio.com/docs/usage/webhooks/webhooks-connection-overrides