This type of callback allows you to automatically receive an update when one of your contacts/recipients unsubscribes from your traffic on SMS.to.

SMS.to provides you this feature by allowing you to set the endpoint in your account settings on SMS.to. You will then receive the callback at the provided endpoint for each status update of messages sent from your account.

You can easily set up the endpoint by these simple steps:

  1. Navigate to your account settings.
  2. Click on the Webhook Management tab.
  3. Save the URL pointing to your endpoint in the Default Optout Callback URL box. It should refer to the endpoint you have set up on your side for receiving unsubscription updates.
  4. Click on Save.
  5. From this point on, your account is ready to automatically receive opt-out updates on your configured endpoint.

We will send you these callbacks using the POST Method as Form Encoded. 

The request body will contain the following information:

json
{
"timestamp": "unsubscription date",
"unsubscribed_number": "opted-out phone number",
"source": "TollFree number or Optout Link"
}
Basic requirements for the endpoint configuration
To receive callbacks from us correctly, please make sure to:
  • Return 200 HTTP Status code when the processing of callbacks is done on your end.
  • Reduce the processing time of callbacks to less than 4 seconds. We drop the connection after 4 seconds and retry sending after 1 hour.


Un-/subscription is not a real-time feature. Actions may take up to 24 hours to come into effect.


Expected callback example:



Read more about SMS status you can expect after sending: SMS Logs & Status


If you have any questions, please send an email to support@sms.to