Solved Flowroute Inbound SMS Callback Accepted (HTTP 204) but No SMS Conversation Created – Hosted SMB v20 Update 9

[MyNew Technologies]

Inbound SMS messages never appear in Chat and no conversation is created.

What I’ve verified

* Flowroute SMS is enabled.
* DID is configured for SMS.
* 3CX SMS provider is configured with the correct Access Key and Secret Key.
* Chat is enabled.
* SIP trunk is registered.
* SMS webhook is generated by 3CX.

Testing performed

* Sending a malformed JSON payload to the webhook correctly generates Event ID 30045 (“Unable to parse message from provider Flowroute”), confirming the parser is active.
* Sending the correct Flowroute JSON payload to the webhook returns HTTP 204 No Content with no parser error, but also no Chat conversation and no Event Log entry.
* Flowroute support captured their outbound callback logs and confirmed the callback is successfully delivered to my 3CX webhook. They have repeated the test multiple times with the same result.
* I also captured the Flowroute callback independently using a temporary webhook endpoint and replayed the exact JSON to the 3CX webhook. The webhook again returned HTTP 204, but the SMS was never processed.

At this point it appears the webhook accepts the request, but processing stops somewhere after the callback is received.

Has anyone seen this on Hosted SMB v20 Update 9 with Flowroute? Is there any additional SMS logging that can be enabled, or is there a known issue affecting the Flowroute provider on hosted systems?

Any guidance would be appreciated.

 

[YiannisH_3CX]

Hello,

If you are routing your DIDs through an IVR then please make sure that the "Forward SMS" option is configured so that SMS messages have somewhere to route.


Also since you are using Flowroute make sure your DIDs are added without "+" and are unique.

Let us know if the issue persists.

 

[Evolute IT]

Hello,

If you are routing your DIDs through an IVR then please make sure that the "Forward SMS" option is configured so that SMS messages have somewhere to route.
View attachment 52030

Also since you are using Flowroute make sure your DIDs are added without "+" and are unique.

Let us know if the issue persists.

The same issue with one of our customers. It seems the webhook isn't even touching the 3CX but Flowroute swears it does, so they don't assist. There's 0 logs in the log files for messaged received, and we tested the webhook via cURL and got the proper 400 bad request (empty body.)

This is since U9 from what I could gather. Because of this, that customer is moving to Twilio.

Not sure why it stopped working so suddenly.

 

[MyNew Technologies]

Hi Yiannish,

Thank you for taking the time to review my system.

That was exactly the issue.

The Forward SMS option in the Digital Receptionist was not configured. Once I assigned the SMS destination, inbound SMS conversations immediately began appearing in the 3CX Chat client.

I also removed the duplicate DID entry with the “+” prefix as you recommended, leaving only the primary DID assigned to the Digital Receptionist.

Everything is now working correctly:

* Flowroute webhook callbacks are being received.
* Inbound SMS conversations are being created.
* SMS routing is functioning as expected.

I appreciate the quick diagnosis. The HTTP 204 callback initially led me to believe the issue was somewhere between Flowroute and 3CX, but the actual problem was simply the missing Forward SMS destination inside the IVR.

Hopefully this thread helps others who run into the same symptom—HTTP 204 responses with no SMS conversation being created.

Thank you again for the excellent support!



Myrin New
MyNew Technologies LLC