Hey, I’ve seen this happen when Vapi’s SMS webhook returns invalid TwiML, causing Twilio to reject or skip the message. I can help review your webhook setup and ensure responses follow Twilio’s XML schema properly. It often just needs minor formatting or response-type adjustments. Also, check if your assistant is sending plain text or JSON instead of TwiML. Are you using Vapi’s default SMS endpoint or a custom webhook handler? @ron