NO_RESPONSE_NEEDED. Whenever this sequence is met, the response generation stops.
You can then prompt the LLM to output nothing by writing something like:
Customize the synthesized speech
Make agent pause and respond with nothing
Keep a Retell agent silent on demand with the NO_RESPONSE_NEEDED stop sequence, so it pauses for the caller without speaking or interrupting.
Sometimes you might want the agent to pause and not respond to the user, like when the user says “hold on” or “give me a minute”. This is a conversational pause where the agent stays silent, not a telephony hold.
We hard-coded a stop sequence in the LLM: