I am currently using a non-verified Toll Free Number (nvTFN) and am having trouble trouble messaging it from a virtual number using the Virtual Phone UI and Studio Flow, which the nvTFN is expected to execute when there is an incoming messages.

For example, when I send a message, say ‘hi’, to the nvTFN, I am supposed to get a response like you see below:

virtual number: hi
nvTFN: Hello, would you like a latte, cold brew, or cappuccino?

The only issue is that there is usually no response from the nvTFN, and it will be rare that it responds as expected. It is only after I refresh the page that the correct nvTFN might appear, and it almost always appears before the message sent from the virtual number, like so:

nvTFN: Hello, would you like a latte, cold brew, or cappuccino?
virtual number: hi

These errors make it difficult to use the Virtual Phone to test out Studio Flows our team makes. When I check the message logs, however, it shows that the nvTFN responds almost immediately to the virtual number message, even though that response is not showing on the Virtual Phone UI.

Moreover, after the the nvTFN response log, there is always a message error for error 30039 going from the virtual phone to the nvTFN. See error log.

According to Twilio’s documentation, error 3309 is in response to what it perceives as machine generated text:

This inbound message appears to be machine generated. Responding to this message programmatically could lead to endless messaging loops. For that reason, Twilio has failed the message with this error code and did not POST to the number's configured TwiML URLs.

We suspect that these error messages are what is preventing the Virtual Phone from functioning correctly. After searching through Twilio’s docs, asking the Twilio AI assistant, and searching through Stack Overflow, we have been unable to understand why this error message is being produced.

Any help, either in fixing the error log, or in fixing the Virtual Phone itself, would be greatly appreciated.