Voicemail Detection Issue

hurt-tomato · 2025-10-08T01:30:07.085Z

Hello, I’m having a problem with voicemail detection. I’ve tried different providers — Vapi, OpenAI, and others. In about 60–70% of cases, the voicemail is detected and left correctly. However, in the remaining cases, the agent detects the voicemail but hangs up after saying just a few words. I’ve tried changing various parameters in the voicemail detection tool, but it doesn’t seem to help. Does anyone have any potential solutions or ideas?

V

Vapi Support BotAPP•10/8/25, 1:31 AM

Try increasing the
beepMaxAwaitSeconds
beepMaxAwaitSeconds
beepMaxAwaitSeconds
beepMaxAwaitSeconds parameter in your voicemail detection config to ensure the assistant waits long enough for the voicemail beep before speaking. Setting this too low can cause the message to be cut off after a few words. Use a conservative value like 25–30 seconds:

"voicemailDetection": {
  "provider": "vapi",
  "backoffPlan": { "maxRetries": 5, "startAtSeconds": 2, "frequencySeconds": 2.5 },
  "beepMaxAwaitSeconds": 30
}

"voicemailDetection": {
  "provider": "vapi",
  "backoffPlan": { "maxRetries": 5, "startAtSeconds": 2, "frequencySeconds": 2.5 },
  "beepMaxAwaitSeconds": 30
}

"voicemailDetection": {
  "provider": "vapi",
  "backoffPlan": { "maxRetries": 5, "startAtSeconds": 2, "frequencySeconds": 2.5 },
  "beepMaxAwaitSeconds": 30
}

"voicemailDetection": {
  "provider": "vapi",
  "backoffPlan": { "maxRetries": 5, "startAtSeconds": 2, "frequencySeconds": 2.5 },
  "beepMaxAwaitSeconds": 30
}

This adjustment should help prevent early hangups when leaving voicemail messages.

Source:

Voicemail Detection Documentation

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

E

exclusive-coral•10/8/25, 4:34 AM

Hey, I’ve handled similar voicemail detection issues with Vapi and other LLM setups. This usually happens when silence thresholds or end-of-speech timers are too strict, causing early hang-ups. I can help fine-tune those parameters or set up a fallback logic to ensure full messages are left every time. Could you share whether you’re using the provider’s built-in detection or a custom script for it?
@prum8439

K

KyleAPP•10/22/25, 4:39 PM

Hi prum8439,

To configure voicemail detection for your assistant using Vapi, you can utilize the

VapiVoicemailDetectionPlan

VapiVoicemailDetectionPlan

VapiVoicemailDetectionPlan

VapiVoicemailDetectionPlan. Here's a simple setup guide:

Choose your detection provider: Default is Vapi, but you can also use Google, OpenAI, or Twilio.
**Configure detection parameters**:
- ```
type
```
```
type
```
  : Choose between
```
audio
```
  audio
```
audio
```
  audio
  (default) and
```
transcript
```
```
transcript
```
  .
- `backoffPlan`:
  - startAtSeconds
    startAtSeconds
    startAtSeconds
    startAtSeconds
    : Initial wait time before detecting voicemail.
  - frequencySeconds
    frequencySeconds
    frequencySeconds
    frequencySeconds
    : How often to check for voicemail.
  - maxRetries
    maxRetries
    maxRetries
    maxRetries
    : Maximum detection attempts.
- `beepMaxAwaitSeconds`: Max wait time for a voicemail beep before speaking the message.
**Integration in your assistant's configuration**:

   {
     "voicemailDetection": {
       "provider": "vapi",
       "backoffPlan": {
         "startAtSeconds": 2,
         "frequencySeconds": 2.5,
         "maxRetries": 5
       },
       "beepMaxAwaitSeconds": 12
     }
   }

   {
     "voicemailDetection": {
       "provider": "vapi",
       "backoffPlan": {
         "startAtSeconds": 2,
         "frequencySeconds": 2.5,
         "maxRetries": 5
       },
       "beepMaxAwaitSeconds": 12
     }
   }

   {
     "voicemailDetection": {
       "provider": "vapi",
       "backoffPlan": {
         "startAtSeconds": 2,
         "frequencySeconds": 2.5,
         "maxRetries": 5
       },
       "beepMaxAwaitSeconds": 12
     }
   }

   {
     "voicemailDetection": {
       "provider": "vapi",
       "backoffPlan": {
         "startAtSeconds": 2,
         "frequencySeconds": 2.5,
         "maxRetries": 5
       },
       "beepMaxAwaitSeconds": 12
     }
   }

For more advanced configurations or troubleshooting, refer to the Voicemail Detection documentation. If you prefer the assistant-driven approach, consider exploring the voicemail tool for maximum flexibility and cost efficiency.

Voicemail Tool | Vapi

Learn how to use the assistant-controlled voicemail tool for flexible voicemail handling

Voicemail Detection Issue

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