i built an ai voice agent using vapi and i have connected it with a twilio number. But the number sometimes works fine. The voice agent talks to me but sometimes it says nothing. how to solve it? 60% of the times the number ans the call but ai doesn’t speaks. And 40% of times it works perfectly. I have also tried to solve it with free vapi numbers. But the problem didn't solve. How can i solve this call silence issue.

Try switching to a faster model or reducing your agent's response length to fix the call silence issue. Go to your Vapi dashboard, select your assistant, and under the

Model

section, choose a faster model (e.g.,

gpt-3.5-turbo

instead of

gpt-4o

) or add a prompt like "Keep responses under 20 words." This quick adjustment often resolves long silences caused by model processing delays. Tip: Test your agent directly in the dashboard to confirm the fix before deploying to your phone number. (See the [Debugging voice agents documentation](https://docs.vapi.ai/debugging) for more details.) Source: - [Debugging voice agents documentation](https://docs.vapi.ai/debugging)

I understand the frustration with inconsistent voice responses, this usually comes from timing issues between Twilio call events and the AI agent processing, or occasional audio stream delays. I can help pinpoint the exact cause and optimize your setup for reliable calls. Have you noticed if the silence happens at call start, mid-conversation, or randomly? This will help us target the fix effectively. @Efran Talukder

@Tremix if the ai agent start talking then i don't face any pronlem. But the main problem is when the call is being started, most of the time the number answers the call without saying anything and the whole call becomes silent. It is happening with my other vapi ai agents too. I have tried twilio, vapi free numbers. But most of the time i am getting this problem. But when ai start speaking after answering the call. Then the call goes smooth without any problem. Thanks for your help.

Got it, thanks for the clarification. This usually isn’t an AI issue, but a call-start timing problem where the call gets answered before the agent or audio stream is fully ready, so the first message never triggers and the line stays silent. Once the agent speaks, everything works because the stream is already initialized. I’ve fixed this before by adjusting the first-message trigger, adding a small post-answer delay, and checking Twilio ↔ Vapi media events. I can help you troubleshoot this directly and get it stable, happy to walk through it with you privately if you’d like. @Efran Talukder

Hey! To help track down this issue, could you share: \- The call ID \- When exactly this happened (the timestamp) \- What response you expected to get \- What response you actually got instead This would really help us figure out what went wrong!