Call webhooks: delivery, retries and duplicates

Last updated: 9 October 2026 · 4 min read

Steps

1. 1

   How to answer

   Answer with 2xx within 5 seconds. Do the slow work (writing to the CRM, downloading the recording) after answering, in your own queue.

2. 2

   When a delivery is retried

   Clomni sends the delivery again when:

   • your server cannot be reached;
   • no answer comes within 5 seconds;
   • the answer is 429 or 5xx.

   There are 5 attempts in all, 30 seconds, 1, 2 and 4 minutes apart. A 4xx answer (for example 400, 401, 404) is taken as final and is not retried.

3. 3

   Spotting a duplicate

   A retried delivery keeps its delivery_id, and the X-ChatX-Delivery header carries the same value. Remember it: if the same delivery_id arrives again, it is a duplicate, do not process it. The pair id + event is also unique per call and works the same way.

4. 4

   After 5 attempts

   If all 5 attempts fail, that event is lost. That is why call_ended carries everything about the call again: even without call_started you can record the whole call from call_ended. Store the call by id and update it on each event.