500 from Retell on Inbound SMS

Support Help
1

Hello,

Background

I recently configured a number for SMS following these instructions:

I am using Twilio with an Elastic SIP Trunk and a number that is in a messaging service connected to a “Verified” A2P campaign. I’ve done the “SMS Add-On”, associated the number to the same agent for inbound / outbound, and created an inbound webhook.

The Bug / Error

I am able to initiate an outbound chat to myself without any errors - I receive the message I would expect to from the agent. However, when I respond to this message, it does not appear in the chat history and I never get a response.

I’ve narrowed the issue down to an ERROR: 11200 in Twilio. I can see a POST request to https://api.retellai.com/twilio-sms-webhook/org_hJfQIvKGkbWArtkE that receives a 500 Internal Server Error back from Retell with no other details that I am able to view.

What I’ve Tried

  1. I’ve double checked the configuration of my SIP Trunk. I did find that I had originally not enabled “PSTN Transfer” so I enabled this.
  2. I confirmed that my number was in the messaging service connected to my verified A2P campaign.
  3. I confirmed the Termination URI for the number was added correctly within Retell.
  4. Since I had made many attempts, I tried ending all of my previous chats in case multiple chats at the same time with the same number was causing an issue.
  5. I purchased a new number, added it to the A2P campaign’s messaging service, reconfigured after trying all of the above with the previous number, and still get the same issue.

Can I get more insight into what the details of that 500 internal server error are? If helpful here are some of the chat IDs from my testing. Most of them should have received multiple “Test” and “Hello” messages:

  • chat_a593fc7009957ac183268759ae8
  • chat_3073ac942eda3369899a6519b98
  • chat_1b61b33b78025ebcb610b7e818a

Thanks in advance for any help!

2

Running into a similar issue. Has this been resolved?

3

Thank you for reaching out to Retell AI Support. We’ve received your ticket and our team will respond within 8 hours.

4

We’d love to get your feedback!

[

Powered by

152×152 1.54 KB

Pylon
](https://usepylon.com)

Unsubscribe

5

Hey Tyler,

What I’ve ended up doing is just managing the Twilio interactions myself. Instead of importing any phone numbers into Retell and using the /create-sms-chat endpoint I am instead:

  1. Adding a webhook pointing at my own service in the messaging configuration for the number in Twilio.
  2. When I receive an SMS from a user, my service will either use /create-chat or /create-chat-completion to start or continue a conversation within Retell.
  3. Gettin the agent message from the chat and send it back to the user via Twilio.

I’m basically having to act as a middleman between the two to provide Retell the user message and then get the agent message from them and send it back.

That being said, I haven’t tried letting Retell manage the number for me in a few weeks, but if you’re encountering something similar still, I’ll guess this is still broken. This Twilio option is the best I found until someone from Retell is able to investigate those 500s on their end (since we get no visibility into those from Twilio).

6

Hi there,

Thanks for reporting this. I’ve escalated the 500 errors you’re encountering to our engineering team for investigation. I will keep you updated.

Regards,
Stanley
Support @ Retell AI

7

Hi sperales, we apologize for the slow response here. We recently fixed a bug that was causing 500 errors on inbound SMS for new chat sessions, but given the timeline of your report we’re not sure if that was the root cause of your issue. Could you try again and let us know if things are working now? If not, we’ll keep digging into it on our end.