thats a tricky one. Maybe by using the call control feature ? Wondering if the call control feature has type setting for stopping messgaes or maybe you get vapi to say "...." or "-" or "" to change the message to something where it doesnt speak. Or maybe use custom llm or custom tts feature since it would send request to your own server which I would assume would allow you to have capability to alter the logic of it and truncate messages when needed