Not all users respond promptly; some might think quietly or get distracted. The agent should handle silences or long pauses gracefully. Typically, IVR systems have timeouts and will prompt the user if they don’t hear anything for a while (“Are you still there?”). In testing, include scenarios where the user is silent for an extended period or says "hold on..." and then nothing. Measure whether the agent follows the expected behavior: does it wait the correct amount of time and then give a gentle prompt, or does it erroneously hang up or say something inappropriate? One can simulate different pause lengths to find the threshold of the agent. The criteria might be that after X seconds of no input, a reprompt is given, and after Y seconds of total silence, the call ends politely. Verify these triggers. Also test if the agent can handle when a user starts talking again exactly as the agent decides to reprompt – this is tricky, but the agent should ideally detect the user’s voice and not talk over them (or quickly stop if it does). This overlaps with interruption handling but specifically focuses on user silence and the agent’s timeout logic.